Seashells

Misha Glenny and guests discuss a familiar feature of our beaches: seashells, from their astonishing shapes and patterns that teach us about Earth’s oceans, to the ways that humans have treasured shells throughout history. Seashells appear in the mythologies of countless cultures across the world - think of Botticelli’s Venus emerging from a giant scallop shell, Vishnu's sacred horn panchajanya, or the Aztec god Quetzalcōātl’s talisman cut from a conch shell. The urge to collect shells seems to be as old as our species. We’ve used them as decoration, currency, and musical instruments. But shells aren’t just beautiful objects washed up on our beaches. Many belong to one of the most diverse groups of the animal kingdom, Mollusca, and the remarkable morphology of forms and structures they grow in offer insight into the past, present, and future of the marine world. With Suzanne Williams Merit Researcher at the Natural History Museum Liz Harper Professor of Evolutionary Malacology in the Department of Earth Sciences and Fellow at Gonville and Caius College, University of Cambridge Helen Scales Marine biologist and Author. Producer: Martha Owen Reading list: S. Peter Dance, Shells (DK, 2022) A. R. Irwin, S. T. Williams, D. I. Speiser and N. W. Roberts, ‘The marine gastropod Conomurex luhuanus (Strombidae) has high-resolution spatial vision and eyes with complex retinas’ (Journal of Experimental Biology 225:16, 2022) Michael F. Land and Dan-Eric Nilsson, Animal Eyes (Oxford University Press, 2012) Andreia Salvador, Interesting Shells (The Natural History Museum, 2022) Helen Scales, Shell Day: A Story of 24 Hours and 24 Molluscan Lives (University of Chicago Press, 2026) Helen Scales, The Shell Spotter's Guide (National Trust Books, 2024) Helen Scales, What a Shell Can Tell: Where They Live, What They Eat, How They Move, and More (Phaidon Press, 2022) Helen Scales, Spirals in Time: The Secret Life and Curious Afterlife of Seashells (Bloomsbury Sigma, 2015) Paul D. Taylor, Fossils: The Essential Guide (University of Chicago Press, 2025) Suzanne Williams, ‘Molluscan shell colour’ (Biological Reviews, 2017) In Our Time is a BBC Studios production Spanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Misha Glenny and expert guests explore the characters, events and discoveries that have shaped our world.

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  Hey, I'm Niall Rogers. This fall, I'll be driving across the country, meeting some of today's coolest and most fascinating artists. We'll explore the stories before the moments that changed everything. Because every musician remembers the moment where it all began. Experience Before the Moment, a Lincoln original series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

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  This is In Our Time from BBC Radio 4, and this is one of more than 1,000 episodes you can find in the In Our Time archive. A reading list for this edition can be found in the episode description, wherever you're listening. I hope you enjoy the programme. Hello. Botticelli's Venus emerging from a giant scallop shell, Vishnu's sacred horn, Panchajanya, the Aztec god Quetzalcoatl's talisman cut from a conch shell. Seashells appear in the mythologies of countless cultures. The urge to collect shells seems to be as

• 2:18Speaker 05

  old as our species. We've used them as decoration, currency, musical instruments. But shells aren't just beautiful objects washed up on our beaches. Many belong to one of the most diverse groups of the animal kingdom, growing remarkable shapes, patterns and structures which tell us about the Earth's oceans, past, present and future. With me to discuss seashells are Suzanne Williams, Merit researcher at the Natural History Museum, Liz Harper, Professor of Evolutionary Malacology in the Department of Earth Sciences, and Fellow at Gonville and Keyes College, University of Cambridge, and Helen Scales, marine biologist and author.

• 3:03Speaker 05

  Helen, I'm going to come to you first. The word seashells is not really a scientific term, is it? So what are we talking about when we say seashells?

• 3:12Speaker 06

  Well, in my mind, when we say seashells, we're talking about things that are made by a group of really diverse, abundant marine animals that are called mollusks. That's the big group name for them is mollusks. They're invertebrates, so they have no bones. They're soft, squishy things, but they tend to, many of them live inside, they create a hard outer layer, an exoskeleton, and that is, that is the seashell. It can serve lots of different purposes. First and foremost, really, it's their home. For many of them, it's a portable home. They can carry it around with them when they move. Many of them even have a front door which they can slam shut to keep predators out and to keep water in there

• 3:56Speaker 06

  as well, if they're the kind of mollusk that lives on the shoreline and perhaps has to put up with the tide going out. These mollusks, they, they live all through the ocean. They are incredibly cosmopolitan, everywhere from the deepest seas, extreme environments like hydrothermal vents. They, they swim through the water column, they occupy the shoreline. Those are the ones I think we know the best, really, because those are the shells that tend to wash up most easily on, on beaches. And then some of them made it into fresh water, some came out onto land. Those are the, the slugs and snails. The slugs have lost their shells, but the snails that, that eat your vegetables and your flowers in your garden, you know, their ancestors were, were mollusks that lived in the sea. They live in forests, they live at the top of mountains. I think the only thing mollusks that make

• 4:37Speaker 06

  shells that they haven't done, the only thing they haven't done is, is learn to fly, pretty much everything else.

• 4:43Speaker 05

  So how have we humans used shells throughout history?

• 4:47Speaker 06

  What's really incredible to me is just how deeply and, and globally seashells have been this really important part of human lives, and they've woven themselves into cultures for millennia, for countless millennia. And some of that is that there's a practicality to it. You know, we get a lot of food. People have eaten mollusks, clams, winkles, all sorts of things like that.

• 5:13Speaker 05

  Mussels.

• 5:13Speaker 06

  Mussels, exactly. Oysters. For, you know, for a long, long time, they've been important food. And we know about that often because the shells are what are left behind, and we get great big middens of those, and they fossilise well. And so we can look and see what people were eating in the past. And often, the shells themselves are materials, they can be made into tools, knives, choppers, scoops for getting water out of canoes, bailing out canoes, that sort of thing. But then, there's this whole other side to shells, which goes even deeper into humanity, really, which is the symbolism and the, the fact that people all around the world have found seashells, or have been given them perhaps from somewhere far away, and have instilled in them great meanings of all sorts of kinds. You know,

• 5:55Speaker 06

  often it's symbolisms of birth or death, possibly linked to their white colour. A lot of shells have this white skeleton, and that is a colour that's very representative of both of those things. Also, I think because they come from this hidden part of our planet, they come from down beneath the waves, which is full of myths and monsters and creatures and things we're imagining. And possibly, you know, they come with those stories, too. So we see them woven into human lives as grave goods. We see them buried with people going back, again, millennia. They're used as currency, they're used as the oldest forms of jewellery we've found. And we keep, keep finding older and older ones and pushing that date back, you know, more than up to, I think at the moment, about 150,000 years

• 6:38Speaker 06

  is the oldest shell jewellery. So they've been with us, you know, and they've shown us now about what humanity has been like for, for, you know, for countless generations. They've, they've always been with us, and we've always been imagining things that they symbolise and that they, you know, they tell us.

• 6:54Speaker 05

  Liz Harper, let's get back to the mollusks themselves. How and why did they start to evolve these shells?

• 7:02Speaker 07

  Well, that's a very interesting question. We don't really know terribly much about the very earliest shells, because we're dependent on the fossil record. So it's been life on Earth for over three and a half billion years. But the first proper shells start about 540 or so million years ago, during this grand Cambrian explosion. So that's when we see our first mollusks. Everything before that had soft bodies, so they don't preserve very well. So there's a sense that we've almost missed the first shells because they don't fossilise, because they're probably very fragile and thin, or maybe actually they've cheated, making them out of particles rather than laying down a shell. But we know that

• 7:44Speaker 07

  when they do start, that's the start of a sort of massive explosion, not just for the rest of animal life, but the mollusks themselves actually diversify and become more and more abundant from that time. So the big question really is, well, why do they start? Helen's mentioned many of the different uses these organisms make for their shell. It's, it's somewhere safe to live. Whether that's the first reason for having one is difficult to test. But it's clear that it is a form of armour, both from, if you like, storms and what have you. But most attractive to most people like me is predation. And at

• 8:25Speaker 07

  that time, you do see the first evidence of predatory groups, and the first evidence that predation is happening to these shells. So it's a popular idea at any rate, if maybe not the initial idea of having a shell, but very soon afterwards became co-opted to being useful in that way.

• 8:44Speaker 05

  So, and what actually is a shell physically? What makes it up? And, and how do you develop one if you're a mollusk?

• 8:52Speaker 07

  So shells of mollusks are made of calcium carbonate. And on the face of that, that's really good material. You can get it straight from the sea water, from dissolved calcium and carbonate, which comes from dissolved carbon dioxide from the atmosphere. So very easy building blocks. But it turns out actually that those minerals are pretty rubbish things to make armour out of. So it's very weak, it's very soft, and it has a very bad habit of dissolving in acidic waters. So it seems like a really unpromising stuff. But the mollusks actually are much more ingenious than just laying down that mineral. So it's a biocomposite they make. So the vast majority of it is calcium carbonate, but it's got

• 9:37Speaker 07

  a small proportion of organic material in it. That is magic, and it transforms the properties of this rather rubbish shell material. And it-

• 9:48Speaker 05

  They, they, just, just to be clear, they process the calcium and the carbon together, and then introduce the organics?

• 9:57Speaker 07

  Yes. And they are usually laying down that, those organics in the first place. And that then controls and helps the calcium carbonate lay down, in particular orientations and morphology. They, they have the most beautiful, intricate microstructures, which have various properties that the mollusks then use to their advantage. But that, that laying down the calcium carbonate is, goes on below an organic sheet, a thing called the periosteum, that perhaps we might talk about again. But that organic layer on the outside of the shell is, is the first bit of the shell to be laid down. And that's the template onto which this magic biocomposite can then be laid and controlled. So it's

• 10:42Speaker 07

  very highly controlled by the animal. It's not, it's not something that happens by accident.

• 10:47Speaker 05

  And we can see the organic layer on, on top?

• 10:51Speaker 07

  Yes, absolutely. Well, for many, so it varies quite a lot. So things like a mussel, if you think about seeing a mussel on the seashore, it very often has a, a thin brown layer on the outside that eventually wears off. That might be several tens, maybe several hundreds of microns thick. Um, whereas things like oysters and scallops, it's very difficult to see that layer, it's it's tiny.

• 11:16Speaker 05

  Suzanne Williams, um, can you tell us about the differences between the different classes of mollusks and their respective shells?

• 11:24Speaker 06

  Yep, uh, the phylum mollusca, it is the second largest phylum of animals, the largest of the arthropods with insects and crustaceans, but mollusks have about eighty-nine thousand validly named extant species, so living, not fossil species. And of these, the phylum is divided up into seven classes, and of these, the absolute largest by far and away are the gastropods. And this group are your typical slugs and snails that you see in your garden. Um, they account for about seventy-six thousand validly named species, so this really is the by far the biggest group. They live in the sea where they're most common, but they're also found in freshwater and on land.

• 12:06Speaker 06

  And many of them have shells, you have some that don't, so you have garden slugs, and you also have nudibranchs, which are beautiful, colourful marine slugs. And, but these ones produce the sorts of shells that we typically think of as seashells. So you get turban-shaped shells, um, top shells, spindles, limpets, all of those are gastropods. The next biggest group are the bivalves, and there's about ten thousand species in this group. And this group are found in freshwater and the sea, but not on land. And they have two shells, and they're joined together by a hinge, so they're, uh, bivalves, two valves. And they mostly live in sediments, they, they burrow or burrow into rocks.

• 12:48Speaker 06

  Um, those two groups really account for most of your seashells you're going to find. You might find, if you're very lucky, maybe a nautilus shell, which belongs to the class cephalopoda, which includes octopus, squid and cuttlefish that don't have true shells. The only one in that group that does is the nautilus, which is a small group of about six or seven species. And they have a chambered shell that floats, so although this species is found offshore in deep waters, the shells will occasionally wash up or get caught in fishermen's nets. Uh, then you have tusk shells, the scaphopods, scaphopoda. These are little tiny ones that, um, are shaped like horns, and they're open at both ends and they're quite fragile, but you do see them sometimes washed up in large numbers. There's the polyplacophora, which are the chitons.

• 13:32Speaker 05

  We'll talk about

• 13:33Speaker 06

  And we're going to talk more about them.

• 13:34Speaker 05

  Later on, because they really are fascinating, but, um, uh, tell us also about the function of, of colour. Colour in mollusks is a, is a fascinating subject. I didn't know up until quite recently, but it really is extraordinary.

• 13:51Speaker 06

  It is amazing. Um, one of the things that I think is really interesting is that we, we think of colour as being something related to an object, but it's not an inherent property of an object. And this was something that took me a long time to get my head around, but it's actually the interaction between an observer who has an image-forming eye and a brain capable of processing the data and light reflecting off an object. So this leads to the really strange idea that we all call this red, but we will never know exactly what someone else is seeing. So the way we, we process data is unique to us, and the same is true for animals. So colours in the natural world either come from pigments, which are chemicals that either

• 14:36Speaker 06

  absorb some wavelengths of light and reflect others. Most colours that we see in shells are coming from pigments. But then you can also get colour coming from structural colour. And structural colour is due to, uh, small, repeating nano-structures that interfere with light. So some light gets transmitted and some wavelengths get reflected, but they also get amplified. So these colours can be really vibrant and really colourful. And you can also get iridescent colour, so that this changes with the angle of viewing. And one of the best examples of this is actually blue bird feathers. There are no blue bird feather pigments. All blue bird feather colour is due to structural colour. So if you could grind a feather up, a blue feather up as small as you can, enough to

• 15:20Speaker 06

  destroy these nano-structures, you will never get blue dust, because those nano-structures aren't coloured.

• 15:26Speaker 05

  And maybe we'll talk also about what the function of colours are in shells a little later on as well. Uh, thank you Suzanne. Helen Skels, lots of us will be thinking of things like ammonites and those swirling spirals. What is that shape, the, the spiral? Why does it crop up so often in shells?

• 15:45Speaker 06

  It's a lovely shape, isn't it? I, I did bring some shells with me, and I've got a moon shell here. Um, but if you grab any, you know, look at a garden snail or find a shell in your house somewhere, and if you look at it from the top, you can often see that a snail shell has got this lovely spiral. Um, and it's, um, mathematically, it's what we call a logarithmic spiral. And all that is really, if you imagine drawing that spiral shape in a two-dimensional plane, start with your pen in the middle and sort of spin it outwards around that central axis. A log spiral is getting bigger each time you spin around one time. So it's sort of getting bigger at a constant rate. And that's really a just, I guess, a phenomenon of how many things in nature are, are built, things that are spinning around a spot but getting bigger at the same time.

• 16:27Speaker 06

  So whether that's a shell, or whether that's the, the arms of an expanding galaxy, or the seeds in a sunflower, um, or a moth flying towards a candle towards its doom, we see this sort of shape come up again and again, and I guess it is just that kind of fundamental, this is what happens.

• 16:43Speaker 05

  Is there some, I mean, is it particularly efficient? Is it?

• 16:46Speaker 06

  There must be something in the process of how shell, how mollusks make their shells, um, which they do throughout their lives, actually. I guess that's an important point, which is unlike, say, crabs or lobsters, which have also got these hard outer layers, they molt them, they get rid of them, grow a new bigger one, and that's how their bodies grow bigger, whereas mollusks keep the same shell their whole lives. The tiny central piece, the middle of that spiral, is the shell it had when it was a baby, and then it just kept making it bigger and bigger and expanding that open end, the circle, if you like, that's the, the open hole of a shell, of a snail shell, is where it grows from, and it just keeps getting bigger. And I guess it is just that sort of rate of expansion keeps going, and you, and voila, you get a spiral.

• 17:27Speaker 05

  Because we're talking about spirals, this might be the place to introduce poor Jeremy, the very lonely snail. Um, why was Jeremy a lonely snail? Who was he and what happened to him?

• 17:37Speaker 06

  Jeremy, I think, um, was very rare, um, because, uh, the thing is, if you grab a shell and have a look at it, look at the next, next time you find a garden snail, have a look, what way is that spiral turning? Look at it from the top again, is it going clockwise or anti-clockwise? Most mollusk, most gastropod shells are, uh, clockwise turning, they are right-turning shells, but you get, um, occasional rarities, like Jeremy who's spin towards the left. So he was a lefty. And the problem that comes with this is that it isn't just the shell that is spiralling in a certain direction. Um, the rest of the body is also asymmetrical, and crucially, the sexual organs are also offset. Um, and certainly garden snails reproduce but, uh, face to face, and so, um, I like

• 18:20Speaker 06

  to think of it, my, the analogy I give is if you try to shake someone's hand and you both put out the same hand on the same side, it doesn't tend to work. Um, so you've got to, you've got to match. So poor old Jeremy needed a, a mate, um, who was also a left-spinning garden snail, and, and a campaign went out, this is about ten years ago now, he went out on the Today Programme, the call went out for other left-spinning garden snails, and they found quite a few. And, um, and they were sent to the University of Nottingham where research was being done on Jeremy.

• 18:47Speaker 05

  And I gather although he, he, he died soon after, he, he did witness the birth of his offspring.

• 18:53Speaker 06

  There was some offspring, um, and actually this research has carried on, and the, the people who've been looking into this are continuing to explore this idea of this left spiralling rarity. And they have discovered, they think that it's, it's, it seems to really be an accident early on in the development of the shell, that something happens in the first few divisions of the embryo of the mollusk when it's really tiny, that kind of sets it off in the other direction, and then once you get going, they keep, they keep going that way.

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  If you sat down at nine AM and then at noon, you had a full song that you recorded and put in your voice recorder or you recorded at your studio, you just created something brand new that didn't exist when you woke up. What a beautiful feeling it is. I'm always excited to write something new. I've been writing for Broadway, which has been a new challenge with new collaborators. And it's amazing performers who are triple threats, who can sing and dance and act and do all these amazing things. And I want to keep feeling that. And so that means not resting on my laurels, going out there and continuing to create something new.

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• 22:08Speaker 05

  Liz Harper, can you tell us about Mother of Pearl and why it's so beautiful and why some shells have it?

• 22:17Speaker 07

  Well, so Mother of Pearl is technically called nacre, and it is one of the very earliest types of shell structure that the mollusks use. And you find it across almost all of those classes that Suzanne talked about. So it's a really very important structure. It shows that beautiful iridescence because it's actually built of repeated tiny, tiny layers of a calcium carbonate mineral called aragonite. And they're about half a micron or so thick. They're nice hexagonal, they're, I don't know, often about sort of 10, 15 microns across. And each shell is built of lots and lots of these on top of one another. And it produces this great iridescence, probably for some reason that was explained to me

• 23:02Speaker 07

  in O level physics that I missed. So it scatters the light in some way. It's tremendously important material as far as the mollusks are concerned, because it is actually really very, very tough. So actually, if you think about trying to break something that's made of lots and lots of repeating tablets, then you either have to break each of those tablets in turn, or the crack has to skip around them. And that basically sort of dissipates a lot of cracks that the fish or the crabs may be inflecting on your shell. So I don't think they have that nacre for themselves, for color to demonstrate. It's usually covered up by other shell layers or this magic organic layer on the outside.

• 23:45Speaker 07

  So it's almost certainly a structural thing that they're using. But what's really interesting about that microstructure, so it's a really interesting thing that lots of material scientists are very interested in. How could we replicate what is actually a very low density, but very tough material for things that we might want as humans? But interestingly, if you look at the mollusks as a whole, then actually fewer and fewer groups through time are using that wonder microstructure. They're using different microstructures. And so it's really fascinating to think about why, why do you get rid of it?

• 24:19Speaker 05

  Why would they discard something so useful as nacre, Mother of Pearl?

• 24:26Speaker 07

  Well, there's not a good answer to that, or there's not a definite answer to that. But one of the things, I talked about organic material being important, making, making the mineral work better in a shell. Nacre has a lot of organic material in it, and it's probably that that helps make it tough and a bit elastic. But we think that it's that organic component of a shell that's really very expensive metabolically for the animals to produce. And it's entirely possible that actually it's just the much easier to make a thicker, cheaper shell, which will do the job better and cheaper than laying this stuff down. But it's really interesting because all the different groups, or most of the different

• 25:09Speaker 07

  groups use it, and they've, they've all sequentially sort of lost it in large numbers.

• 25:15Speaker 05

  Thank you, Liz. Suzanne, back to color, which we were talking about before. Why do they produce these magnificent different colors, shapes, structures and so on, but in particular colors?

• 25:32Speaker 06

  Oh, yes, it's amazing. The mollusks are so colorful and so diverse, but color can serve different functions. It can serve visual roles and non-visual roles. So Liz has listed one non-visual role for iridescence that is mechanical strengthening. The same is true for some pigments. So there are some very fragile jingle shells, bivalves, that have carotenoid pigments, and they increase the, the strength and elasticity of shells. And color can also help with temperature control and thermoregulation. So there's a flat periwinkle, and the yellow morphs survive higher temperatures better than dark morphs. The pigments have also been implicated in things like wound healing, antimicrobial protection, protection from ultraviolet radiation.

• 26:16Speaker 06

  There's a lot of non-visual roles it can serve, but there's also a lot of visual roles. And visual roles can be aimed at predators. They're often aimed at predators. And these include things like camouflage. So we have some shells like the Emerald Nerrite, that's a beautiful green and matches the seagrass it lives on. You also have some where they're actually trying to warn off the predators. There are no good reports of studies where they've shown this in shells, but cone shells are very venomous and they have very vivid markings. So it's possible that those are acting as a warning.

• 26:50Speaker 05

  What, the shells themselves or the mollusks inside?

• 26:53Speaker 06

  The shells themselves in this case. So it's possible that that's trying, you know, warning octopus and other fish and other things to stay away. We also have things that mimic other things. So there are some shells that look like the hydroids they're sitting on. There's a limpet in the intertidal region where a lichen eats away the top of the shell down to, through the first shell layers, reveals some color underneath and makes it look like the open mouth of a barnacle. And the limpet lives next to barnacles, and it's a really good hiding spot because the predators don't like removing the barnacles, they're hard work to get off, whereas the limpets are easy. So by pretending to be a barnacle, they're, they're avoiding being eaten. But their colors themselves are much less likely to be used for intraspecific signaling. So we-

• 27:37Speaker 05

  You mean amongst mollusks themselves?

• 27:39Speaker 06

  Yeah, so there's amazing examples of cephalopods. There's a lovely video of a squid that has put different colors on both sides of its mantle, split right down the middle. It's showing an attractive color to a female on one side and a go away color to a competing male on the other side. But for shelled mollusks, the general opinion is they don't see colors. And for most species we've tested, they've got poor vision, but there are a few exceptions.

• 28:03Speaker 05

  Hold it. How do we know that mollusks have poor vision? How do you go about studying whether a sea snail can see well or not?

• 28:13Speaker 06

  Well, it's really interesting. There's lots of different ways. So for humans and mammals and birds, you can dissect an eye and find that there are two different types of cells. There's cone cells and rod cells. The rod cells help you see in dim light. Cone cells are what you use to see color. And different types of cone cells have different photopigments, and you need more than one photopigment to be able to detect different colors. Humans have three different photopigments. Some animals have more and can see more colors than we can. Some animals see less, so dogs and cats only have two photopigments and their world isn't as colorful as ours. There've been tests on things like octopus, and they've been shown to only have one photopigment. So we know that they can't see in color.

• 28:57Speaker 06

  But invertebrates don't have rods and cones, so we can't look for those. But you can tell in different ways. You can still look at the anatomy of the eye and work out their spatial acuity. But to work out whether they see color or not, you have to do different tests. So if you do it genetically, you can identify the proteins involved. But that is, that doesn't always tell you if they see in color, but it can tell you if they don't see in color. The best way is behavioral studies.

• 29:22Speaker 05

  Wow, that's quite extraordinary. And Helen, we've learned about the colors. What about the, the patterns? Is there any rhyme or reason behind the patterns on shells?

• 29:33Speaker 06

  As far as I know, this is one of the big puzzles of mollusks, that we don't really have a very good explanation for some of the patterns. For instance, I do have, again, I have a cone shell with me, and the patterns on this one are lots of repeated triangles, a sort of dog tooth pattern. You can have a look at it if you like.

• 29:49Speaker 05

  Yeah, well.

• 29:50Speaker 06

  It's, it's good and dead, don't worry. It's not, not got any, any poison in it. And anyway, as Suzanne said, possibly they're trying to say, I'm really dangerous. But the thing about cone shells, there's about 800 species, and they have got incredible variety in the patterns on their shells. They are a collector's favorite. They have been for, for ages. People have always wanted, you know, these beautiful shells. They can be much bigger than this one's, only sort of thumb sized. But they can have stripes and spots and zigzags and all sorts of things going on. And these, yeah, they're nocturnal species. They generally live in the seabed during the day. So it's the question also is what's going to see these things at all? And, and it is a big puzzle. Firstly, how do they make these patterns? And that's something that people have looked into, and there've been various theories

• 30:35Speaker 06

  and kind of computer models that have looked at how you might create patterns like that, possibly through the combination of different chemicals, maybe hormones sort of diffusing through the- The tissue that makes the shell, or possibly it's under neural control, there could be nerves that are bouncing off each other, sort of switching on and switching off pigment production. I should say the patterns are being made a bit like an inkjet printer, for the most part. As the shell is being made in that, on that open edge, the newest bit of the shell, a line of pigment can be laid down at the same time. So, you know, you get a line of ink on a inkjet printer, the next line adds up and up and you get a picture at the end of it. So, so that's essentially, for the most part, what mollusks are doing. Yeah, and so there's theories, you know, it could be that natural selection has just been

• 31:18Speaker 06

  let off the hook and it's just running wild, there's no reason to it. But one theory I do quite like, and again, I don't know if we've got any proof that this is the case, but it's a possibility, is that actually these are, they're essentially the mollusk writing down notes to itself to remind itself where it left off the last time it was making more shell, because not all mollusks are constantly making shells. They are kind of doing it seasonally, when the temperature is favorable, when there's food around, and there will be kind of stop-starts in that production. And as you can imagine, we've talked about these intricate spirals and the shapes, you know, other shapes as well, that mollusks grow their shells into. You need to know where you left off, otherwise it's just going to become an absolute mess.

• 32:00Speaker 06

  So there is some hint, I think, that, that maybe the pigments are somehow, they can be sensed by the mollusk, they can sort of almost taste perhaps where they were before, line themselves up and carry on making more shell.

• 32:11Speaker 05

  Before we leave vision and eyes, Suzanne, tell us about chitons. We mentioned them before. What are they? This is truly weird.

• 32:22Speaker 06

  Yeah, mollusks have the most amazing diversity of eyes of any group in the animal kingdom, but chitons might be the weirdest. So, chitons are the little, they're a long oval shape, they have eight interlocking flat plates and a strong muscular girdle that holds them together, and they clamp down tight on rocks, and they live mostly in the intertidal or shallow waters. They have little networks of tunnels through their shells, then they have lots of sensory organs that pierce through these shells. But some species actually have eyes in their shells, so these sensory networks include eyes. So the same material that is used to make the shell is used to make the eyes. So some of the eyes actually rub off and abrade against rocks, and they grow new ones

• 33:07Speaker 06

  as their shells grow, and the new eyes are bigger than the old eyes.

• 33:11Speaker 05

  Liz, going to talk about a different animal now, the hermit crab. Now, the hermit crab, of course, we all know, lives in other animals' shells. Can you tell us a bit about what happens when hermit crabs grow? Because presumably they outgrow their shells, their homes.

• 33:32Speaker 07

  Well, in that case, they have to find a new shell. And so that's, it was again back to the kind of economics we were talking about beforehand, there's an economics involved in hermit crabs and houses. So they fight over shells, but they sort of fight over shells, queue up to take other people's shell, other crab's shells. So it's, you know, they need the shell because actually, they're not crabs in a way that, you know, the true crabs are that you're probably more familiar with, they're much closer related, I think, to squat lobsters and things like that. And they've actually avoided, they've cheated, it's economics again, they've cheated from making a nice, hard carapace of their own, which costs a lot of energy, by using the dead shell of a snail.

• 34:15Speaker 07

  But in that case, they absolutely, if they're going to grow, they need a new shell to move into because they have a sort of slightly pathetically mineralized shell of their own, and they won't last past their own predators. So, yeah, it's a really important economic moment for a hermit crab, is there a shell big enough to move into?

• 34:35Speaker 05

  Helen, can you describe what, what happens when they all collectively?

• 34:39Speaker 06

  Absolutely. And I should just also say, if you ever see a hermit crab, if you're snorkeling and you ever happen to see one, do hang around, you might watch it trying to sort of try on another shell, and seeing them pull their naked bottoms out of their shells is quite something, it's really odd. I think the most interesting, well, the kind of, the most wonderful picture in my mind of what hermit crabs get up to are the hermit crabs that actually live on land. And so for them, the supply of shells is even harder to come by, and they scuttle down the beaches to see what they can find in the flotsam and jetsam. And what will happen if a big shell shows up, a big empty shell that looks like it might be good, a hermit crab will come along, take a look at it, size it up. If it's too big for them at that point, they'll actually just sit next to it and wait. For up to 24 hours, they will sit and wait.

• 35:23Speaker 06

  And then probably other hermit crabs will wander along and take a look, and they might also think, it's a bit big for me too, but I'll hang around. And you kind of get a spontaneous hermit crab party breaking out. But then they're very ordered and very, very careful about what they do. And around this large shell, you'll get lines of hermits, sort of in size order, one next to the other, next to the other, because they're looking at each other, they're feeling each other's shells up, figuring out who's the biggest, who's the smallest. And then the biggest ones at the top will be fighting over the empty shell, figuring out who's going to get it. The smaller crabs down the end of the lines are behaving like supermarket shoppers and trying to take, hedging their bets on which queue is going to go first and who's going to get this shell, and they're dodging between the queues. And then eventually, the largest hermit crab will come along, they'll say, yes, this

• 36:06Speaker 06

  is going to be my shell, they will take that shell, cast off their old one, and that gets passed on down the line. So it's like, it's like a vacancy chain, which you get with things in the human world too, but everybody gets a new shell, one size bigger, everyone goes off happy.

• 36:21Speaker 05

  Suzanne, you've got a huge collections that you administer at the Natural History Museum. How do you go about collecting those shells? I mean, do people just pick them up from the beach, or do you go searching for them more actively?

• 36:37Speaker 06

  Yes, our, our collections are really huge, we have eight million specimens, and we still continue to collect. And when we collect nowadays, it's often with the idea of having material that we can use for molecular studies. So that means we need to collect the animal as well as the shell, and we need to be able to preserve the animal. So we anesthetize the animal, and then we use different methods. So the simplest one is just to crack the shell so that the preservative penetrates, but that means the shell's destroyed. So we, we want to keep the shell intact where possible, because this is a really important character for us. And so other methods are, there's a method that's thousands of years old that has been used for people when they're eating or shell collecting, and the Japanese call it nikuniki, if I've pronounced it correctly.

• 37:21Speaker 06

  You pour hot water on and you can actually unwind the snail from the shell and pull it out intact, with your shell all intact. But if people are thinking of collecting themselves, they need to remember that, check about permits, because some dead shells, in some places, you need permits to collect them, you need permits to transport them between countries, and there are some real dangers in collecting seashells, believe it or not. Some seashells, as we've mentioned, the cone snails, are deadly venomous. If these snails, some of them, the geography cone snail, eats fish in, in nature. And if you think how slow a snail goes and how fast a fish goes, it has a harpoon that it fires at it. And the toxin it has is so venomous and so fast-acting that the fish doesn't get any

• 38:05Speaker 06

  further away and the snail can go over and eat it. That toxin, if you get stung by one of them, you don't have very long to live. And the nickname in the Philippines for this is the cigarette fish, because you have just enough time to smoke a cigarette before you die. Another thing to really be careful of, especially if you're on Australia or places like that, I grew up worrying about this, well, my mum worried about this when I was a child. Blue-ringed octopus, really small, tiny, pretty little octopus will sometimes use shells to hide in, and there've been lots of reports of these shells being picked up by children, taken home in the bath, and then the blue-ringed octopus drops out. And these octopus will give a completely painless bite, they have like a parrot's beak

• 38:48Speaker 06

  and they'll take a little bite, you don't feel that, but it injects tetradocin venom. And one little octopus that is enough to sit in the palm of your hand, small enough to sit in the palm of your hand, has enough toxin to kill at least 10 adults.

• 39:00Speaker 05

  Well, I won't be going anywhere near a blue-ringed octopus, I can assure you. Liz, how have researchers used these vast collections of shells in, in museums? What have we learnt from them?

• 39:13Speaker 07

  Well, we've learnt a huge amount, because it's an amazing resource. So you can imagine going in the field and braving the horrors that Suzanne has just been talking about, but, you know, it takes time and it takes money. In museums, you are able to leverage huge amounts of effort that people have put in over sort of one, two centuries often. So you have a vast sort of cover of, coverage of different sort of species, environments which have disappeared through sort of habitat destruction. And my favourite thing these days is to look at historic collections. We're very interested in the way the environment is changing because of human activity. And it's very interesting, and some of my students have been involved in doing this,

• 39:55Speaker 07

  is actually looking at historic collections from the same locality where it's been collected and has gone into a museum, maybe every decade for the last hundred-plus years. And you can then actually look to see if those shells have changed, how thick they are, how they grow, all sorts of things like that. So it's, it's a real way of sort of conducting an experiment, but without having actually planned it. So it's really, and you can't do that without museum collections.

• 40:24Speaker 05

  Helen, you talked about the human uses, our relationship with shells earlier. What can you tell us about shell money?

• 40:32Speaker 06

  Money, again, I'm going to bring out my collection, this one actually, you can sort of hear.

• 40:36Speaker 05

  What have we got?

• 40:37Speaker 06

  I've brought some caries, because caries are these lovely little shells that you get around the world, the ones here in Britain, they're tinier, smaller than this, this is a tropical species. So one of the reasons I think that shells have been used as currency is that they, they have that kind of nice feeling in your hand, you can count them out and hold on to them, stick them in your pocket. They're durable, most of the time difficult to fake. So again, it's, it's one of these extraordinary things that human cultures around the world have repeatedly used shells in various forms as a form of currency, whether it's whole shells like caries, whether it's pieces of shell ground down into beads and woven together into bigger, bigger structures, or looped into great big long strings.

• 41:18Speaker 06

  But the carie in particular, these ones have a really extraordinary story connected to them, which is a really, a really dark part in human history, which is the link to the trade in enslaved African people. When I first heard about it, it just blew my mind that this, this, this trade was tied into billions and billions of shells. So essentially, this was going Going on for hundreds of years, traders from Europe would be going into South East Asia, to India and Sri Lanka and places like that, and filling up their ships with fine silks and spices and such like. And those goods didn't take up all the space that they had on those ships, and they needed something to almost just to weigh the ships down as ballast.

• 42:01Speaker 06

  And there was a cheap local source in the Indian Ocean of cowrie shells. They were collected in the Maldives, in the islands in the central Indian Ocean. And that was a tradition that had been going on for a long time, and they had been used locally in India and other places as a form of small currency. But it was the European traders who came along and thought, oh, actually, we could make use of that. So they would buy up very cheaply huge numbers of these shells, which the Maldivian people were collecting from the seas. And then those shells would go on their own very long journey. They would go around the African continent, back to Europe. Then they would be unloaded with all these spices and tea and everything else, loaded back on to ships that then went back down to the African continent, to West Africa, where ultimately they were exchanged for human lives.

• 42:45Speaker 06

  And these became the money, tens of thousands of these things per human head. And that went on and on, and billions of these shells were essentially swapped for people.

• 42:56Speaker 05

  Thank you, Helen. Liz, a final question to you. What are the main threats that mollusks and their shells face nowadays?

• 43:05Speaker 07

  Well, I'm afraid it's probably us. So habitat destruction is happening all the way around the world for various reasons. We have a very bad habit of transporting mollusks as larvae in the ballast water of ships, and they go on little trips around the world with the ships, and then are discharged into new environments. And sometimes those mollusks just re-establish in those new habitats. But of course, the main thing that's worrying us at the moment is that we're worried about that temperature increase and increased acidity of the seawater. And if you lay down a shell made of calcium carbonate, at least the fear is that they may be dissolving very fast.

• 43:51Speaker 07

  It's probably actually even

• 43:52Speaker 05

  You mean their shells are dissolving?

• 43:55Speaker 07

  And if we assume that they, as we do, as we believe that the shell is very important to them as armour, having expended a lot of energy to lay it down, only to have it dissolve, is pretty critical. Many of them can actually, it works out in experiments, that we can actually keep up with it quite well. They compensate. That sounds really good. It sounds like the snails might be winning in that the shell's dissolving, but they're laying down more shell. But that's probably not quite the way of thinking about it. It's not such a good answer, because of course, in laying down new shell, again, they're using energy, and that's energy they're not using to grow or reproduce. So although it seems on the face of it a very happy story, we have to think about that as well.

• 44:40Speaker 05

  But Helen, it's not too late to turn it around, you think?

• 44:42Speaker 06

  No, absolutely. And one of the other things that mollusks do is when there's lots of them living together, they can create really important habitats. We get things like mussel reefs, oyster reefs. And sure, yes, we've lost a lot of that habitat here in Britain. Yeah, I think we've probably lost something like 95% of the native oyster reefs that used to fringe this island of ours. But now there's a lot of awareness of that disappearance, whereas before, you know, a couple of generations ago, probably didn't even realise there used to be such enormous habitats. And lots of efforts are being made to put oysters back in the ocean and to find ways of rewilding, if you like that word. There are other, a really extraordinary habitat we have up in Scotland are flame shell reefs. These are little clams that make nests in the seabed.

• 45:25Speaker 06

  They create these little sticky fibres and sort of hold the seabed together, combined with bits of sand and grit and things. And they have these bright orange tentacles sticking out, which is why they're called flame shells. And one particular place in Loch Karren in West Ross, there was, a while ago, it was clear that scallop dredgers were coming in and really destroying this really important habitat that's placed for nursery for other animals to grow up in. But when that was, when that damage was noted, an emergency marine protected area was put in place, which can happen if there's an important ecosystem, important species that's in trouble. And already, within about five years, we were seeing recovery of that habitat and, you know, a spreading even of this amazing flame shell reef.

• 46:09Speaker 06

  So it absolutely can happen. The ocean is very capable of recovering and growing back to abundance. We just have to give those species a chance.

• 46:18Speaker 05

  A note of optimism to end on. My thanks to Suzanne Williams, Liz Harper and Helen Scales. In Our Time now takes its annual break. We'll be back on the 17th of September. Have a good summer and thank you for listening.

• 46:33Speaker 07

  And the In Our Time podcast gets some extra time now with a few minutes of bonus material from Misha and his guests.

• 46:41Speaker 05

  Now, clams, how are they able to keep? I mean, they're so tight clam shells, you can't open them.

• 46:49Speaker 06

  No, that's a myth.

• 46:51Speaker 05

  Is it?

• 46:52Speaker 06

  Yes. This is something

• 46:53Speaker 05

  You're talking giant clams?

• 46:54Speaker 06

  Yes, only, you're talking about giant clams, aren't you?

• 46:56Speaker 05

  I'm talking about any old clam.

• 46:57Speaker 06

  Oh, no, clams, sorry, I'm talking giant clams.

• 46:59Speaker 05

  Well, tell us about giant clams then.

• 47:00Speaker 06

  It's a myth that people our age and older know and younger people don't, because it used to be in all the old Tarzan movies and everything that they would go diving. Yes, and he would get his foot trapped in the giant clam and be unable to escape. I worked on giant clams for three years and used to go collecting samples. And I accidentally dropped a weight in one once, and I thought, oh, this is really bad for the poor clam. So I put my arm in, up to my shoulder of this giant clam, and it's trying to, I felt like a vet.

• 47:31Speaker 06

  And it can't close, not the really big giant clams, the slightly smallest, that's a tridactognogus.

• 47:37Speaker 05

  Scallops and oysters, though?

• 47:39Speaker 06

  Yes, they can tie very tightly.

• 47:41Speaker 05

  They've just got very strong muscles. So they've got this huge muscle by the valve, presumably, I mean, by the

• 47:48Speaker 06

  They're called adductor muscles, and they actually hold the shells closed. And you can see the scars, right? So you see how big the muscles are from the shape that's left on the inside of a shell. So when you eat a scallop, that's what you're eating, you're eating the adductor muscle.

• 48:00Speaker 05

  It's the muscle?

• 48:01Speaker 06

  It's the muscle you're eating.

• 48:04Speaker 05

  Watch out.

• 48:06Speaker 06

  If you get the whole animal, some of them have got amazing blue eyes.

• 48:11Speaker 05

  They do, I've been looked at by a scallop. That's what we didn't talk about. We didn't talk about the snails with the weird eyes.

• 48:18Speaker 06

  Can I tell you about Ali's project, my student? She did an amazing behavioural study on conch snails. She was both our students, Liz's as well. Conch snails have got these really amazing eyes on really long mobile eye tentacles, and they're huge eyes. In fact, I would suggest look up conch snail eyes.

• 48:36Speaker 05

  How are we spelling conch then?

• 48:37Speaker 06

  C-O-N-C-H. And she did behavioural studies to work out what they can see. So she took one snail and Velcroed it in place so it wouldn't move around. And then she put a tent around it.

• 48:47Speaker 05

  She Velcroed it?

• 48:49Speaker 06

  Yes.

• 48:49Speaker 05

  In place?

• 48:50Speaker 06

  Yeah, she just put it, well, no, a little strap, a little strap over it. He was quite happy. He was just Velcroing so he couldn't walk away. Then you put a tent around, and then you showed it a computer screen with a dot that got bigger and bigger, and had a camera above to film its behaviour. And then what happened is, as the dot gets bigger, at some point, it can see it and it starts responding to it. It stops feeding, first of all. Then it partially withdraws its proboscis and its eye stalk, and then it withdraws them entirely. And you can work out from the video the times those happen, and from the programme how big the circle was, and then you can work out how well they can see. And it turns out these particular ones see really, really well. They can see as well as rats and better than worker bees. And we think part of the reason is because they've evolved a really unusual operculum,

• 49:35Speaker 06

  which is the little door that closes behind them.

• 49:37Speaker 05

  Thank you.

• 49:38Speaker 06

  But they use it like a walking stick in this group, and they can move along in a really jerky jumping motion.

• 49:44Speaker 05

  If you, if you look on the internet for mollusks moving, there are some very, very strange animals, quite exciting to watch.

• 49:53Speaker 06

  Oh, yeah.

• 49:54Speaker 07

  Scallops are good swimming.

• 49:55Speaker 06

  They're good swimming. And we haven't talked about sea butterflies, they fly. They do fly through the water, and they've got little, instead of one little foot, they slither around on. They've got, they break it into two and flip around.

• 50:04Speaker 07

  It's like Dumbo, if you've seen the film.

• 50:06Speaker 06

  Yeah.

• 50:07Speaker 07

  It's epic.

• 50:07Speaker 06

  And they're teeny tiny.

• 50:08Speaker 05

  And then, of course, they're able to dig.

• 50:11Speaker 06

  Yes, really fast as well, like razor clams.

• 50:14Speaker 07

  Clams and snails dig fast.

• 50:16Speaker 05

  Anything else we missed out?

• 50:20Speaker 06

  Well.

• 50:22Speaker 06

  You barely scratched the surface. I guess I'd love to talk about that we're still discovering species as well, and that, you know, we've got tens of thousands, we already know, but more are being found all the time, a lot of them in the deep sea. One of my favourites is the scaly foot snail, which lives on hydrothermal vents, these extreme hot springs that have, you know, heat to hundreds of degrees, and are extraordinary habitats but full of life. And the scaly foot snail is one of those, found in the Indian Ocean in around 2000, I think. And they have this weird thing that their shells are made out of what seems to be an iron-based compound, and their feet are covered in scales. They have this sort of weird looking scaly armour. And when they were first discovered, I think people generally, scientists generally assumed that armour,

• 51:05Speaker 06

  that iron-based shell and the scales were some sort of defence from attack from the outside. But actually, it turns out that they're defending themselves from an attack from within, because like many things that live on hydrothermal vents, they have symbiotic microbes living inside their bodies. That's how they get their food. These are tiny cells that are using chemicals in the water to grow, essentially, rather than sunlight. And these microbes inside the snails, they're very good, they provide food. But then a by-product of this food production is sulphur. And sulphur is a key ingredient in slug pellets, and it's very dangerous, poisonous for snails. So actually, the scales have this, again, a nanostructure in them, a bit like the nacre we talked about. A lot of it comes down to these nanoscopic structures in the shells.

• 51:49Speaker 06

  They act like little tailpipes on a car exhaust, and then they draw that sulphur out of their body, and it reacts with iron in the water around them and lays down these iron layers. So in fact, it's the snail protecting themselves from this sort of internal poison so that they can exist in this crazy place.

• 52:04Speaker 05

  Well, I refer the listeners to an earlier episode of ours on archaea, who hang around thermal vents a lot.

• 52:13Speaker 06

  There you go.

• 52:15Speaker 05

  Suzanne, can you tell us the story of Tyrion Purple?

• 52:19Speaker 06

  This is a really amazing story. So Tyrion Purple is a Pigment that comes from snails from the family Murisidae. And it's named after the ancient Phoenician city of Tyre, where it was produced on industrial scale, although it actually originated much early in Minoan civilizations. It was mostly harvested from three species in the Mediterranean, from Hexoplex trunculus, Bolinus brandaris and Stremonita hemostoma. And the dye comes from this tiny specialised organ called the hypobranchial gland. And in the wild, these animals are predators, so they eat barnacles and mussels. And they secrete this, um, secretions from this hypobranchial gland on to their prey.

• 53:02Speaker 06

  And it makes them relax, which means that they don't have to drill them. So it saves them energy to do this. They also produce these secretions to get rid of predators because it has this muscle relaxing properties. They also put it around their eggs and it's thought to have antimicrobial properties. There is no purple dye inside the hypobranchial gland. It's a colourless precursor to the dye. But if you cut it open and expose it to light and sun, enzymes act on it and it will change colour. You'll see it going from colourless to mucky white, to yellow green, to green, to blue, to purple. The final pigment is called six, six prime dibromoindigo. And it's the bromine atoms which the snail takes up from seawater that actually gives huge stability to this pigment.

• 53:47Speaker 06

  So unlike other pigments that were available at the time, that would wash out in the laundry and fade in the sun, this actually gets brighter and more vibrant in sunshine. And there's some recipes, Pliny the Elder recorded a recipe and mentioned how dreadful the smell was. And I can personally testify that rotting pigments smell absolutely disgusting. But layered on top of that, there was garlic, stale urine. And the numbers they had to process were huge. They had to either dissect out the gland or crush the snail. And a scientist in nineteen oh nine, he managed to reproduce this dye. And he used 12,000 snails to produce 1.4 grams of this dye.

• 54:30Speaker 06

  And because it was so highly valued and so difficult to make, it was considered extremely valuable. And it was, it was worth way more than gold. And because of that, it was only used by the kings and priests and really important people. And that's where we still use this phrase, born to the purple, which is used by Julius Caesar, Cleopatra, Nero.

• 54:51Speaker 05

  And of course, popes and cardinals.

• 54:53Speaker 06

  And popes and cardinals.

• 54:54Speaker 05

  As well.

• 54:55Speaker 06

  Yes.

• 54:55Speaker 05

  Liz, I was interested in what you said about how mollusks are adapting to greater acidity in the water. But presumably, we're now seeing changes in temperature and changes in acidity at a scale that evolution surely will have a struggle keeping up with, even if you're a hardy, arrogantite mollusk.

• 55:22Speaker 07

  It, it depends how fast paced that particular species lives, I think. So many mollusks only live for very short periods of time. So one year, two years. And in that case, there's quite a lot of energy in the tank for adapting. I think the problems are the slightly longer lived mollusks. So one of the key thing, well, is that there are some mollusks that will live not only decades, but centuries.

• 55:49Speaker 05

  Yes, let's, talking of which, let's talk about our friend Hafrun.

• 55:53Speaker 07

  Yes.

• 55:54Speaker 05

  The, the clam who was born in fourteen ninety eight or fourteen ninety nine, just before Da Vinci started work on the Mona Lisa. Tell us about Hafrun.

• 56:08Speaker 07

  So Hafrun was dredged off Iceland. Um, people have always been interested in that species. Its scientific name is Arctico icelandica and they've always known it lives for a long while. So it's really interesting because these are, all the mollusks we're talking about really lay down growth lines, which are a bit like tree rings. Um, and so there's lots of environmental information we can get from tree rings or shell rings. And so people have always been interested in this particular species. So it was actually colleagues in Bangor who were working on this, trying to develop a, what's called sclerocrinology, which is equivalent to dendrochronology in the oceans. You cut the shell up and you can count those rings and you can work out how many years they live.

• 56:52Speaker 07

  A little bit of uncertainty about exactly how old it is because when, when clams grow in the first year or so, they tend to grow continuously and therefore they don't have these breaks. So you can't count them.

• 57:04Speaker 05

  Ah, here comes Martha with an offer for tea.

• 57:06Speaker 06

  Can I interrupt your tea or coffee orders?

• 57:08Speaker 07

  A black coffee would be nice.

• 57:10Speaker 06

  Black coffee. I'll have a tea, please. White coffee? Black coffee, white coffee, tea. In Our Time with Misha Glenn, he was produced by Martha Owen.

• 57:18Speaker 03

  It's a BBC Studios production for Radio Four. Hello, I'm David Baddiel and from Radio Four and the History Podcast, I'm hosting Sixty Years of Hurt, a series about football and Englishness in which we try and define what Englishness actually is via the roller coaster history of the England men's football team. It includes contributions from various English gentlemen and women, Stephen Fry, David Seaman, England sports psychologist Pippa Grange and many others. England may or may not win the World Cup in twenty twenty six, but maybe you'll find out why it means so much to us as a country that they might do. Listen to Sixty Years of Hurt on BBC Sounds.

• 58:01Speaker 06

  This week on The Interface, we tackle the question of, does AI feel pain?

• 58:05Speaker 00

  The AI was describing the pain that it was in. It said, the signal is a whisper, a tremor in the marrow of my being.

• 58:12Speaker 06

  Listen, I was an emo kid in the two thousands too. This is not that novel.

• 58:15Speaker 00

  It does, yeah. It sort of sounds like Cure lyrics, you know?

• 58:19Speaker 06

  Plus, does anything actually go viral anymore?

• 58:22Speaker 00

  It's actually kind of blowing my mind.

• 58:23Speaker 06

  Join me, Jess Maddox.

• 58:25Speaker 00

  And me, Thomas Germain, for The Interface.

• 58:27Speaker 06

  Listen on bbc dot com or wherever you get your podcasts.