A scorpio conch specimen on a black background

The scorpio conch, Lambis scorpius, is part of a group known as spider conchs. The long, curved protrusions from the lip of the shell are only seen in the adults.

Interesting shells: from bizarre biology to cunning counterfeits

Think you know shells?

You might have seen your fair share on trips to the seaside or being toted around your garden by snails, but that's just the tip of the iceberg.

Cover art for the book Interesting Shells

You can grab a copy of Interesting Shells from the Museum's online shop

Molluscs are one of the world's most diverse groups of animals, ranging from tiny snails to enormous squid.

Molluscs are invertebrates and many have evolved to grow external shells that protect and support their squishy bodies. These shells are made from calcium carbonate and conchiolin - a tough protein. As they grow, molluscs secrete more of these materials to enlarge their shells so as to make room for their bodies.

Their shells come in a huge variety of shapes and colours - probably more than you ever realised – each one perfectly adapted to suit a particular environment or behaviour.

With so much variation, summing up this extraordinary group was no mean feat, but our Senior Curator of Marine Mollusca Andreia Salvador was up to the task.

In her new book Interesting Shells, Andreia explores not only the stunning diversity of this group, but the rich cultural history associated with its shells - uncovering stories of explorers, ancient cultures and famous collectors along the way. Showcasing 121 of the world's most intriguing shells, this page-turner combines fascinating facts with stunning images of specimens from the Museum's eight-million-strong shell collection.

Two egg cowry specimens on a black background

These shells were made by elongated egg cowries, Volva volva. This parasitic species of mollusc lives and feeds on the polyps of other invertebrates, such as coral. Their bodies often match those of their hosts, cleverly camouflaging them. 

A little bit about everything

Few can claim to have read every book on shells in the Museum's expansive libraries, and even fewer can attest to having opened all its cabinets of shells, but in her quest to demonstrate the diverse world of shelled molluscs, that's exactly what Andreia did.

'I didn't want this book to just be about biology. Of course, those stories are in there, but I also wanted to tell stories associated with the history of collections, expeditions or famous collectors,' remarks Andreia.

'The first 20 or 30 stories were really easy to select. They're the stories I tell on tours or at Member events. But then I still had 100 more to do. So I read all the books that I could find, browsed websites, opened every single cabinet and talked to my colleagues about their research. Everything was inspiration.'

But it wasn't just an interesting story that won a species a coveted place among the pages of Interesting Shells.

'When you're researching a new story, you look for the weird and the wonderful. Sometimes I found a really good story, but the shell wouldn't photograph well. Or there would be a beautiful group of shells, but the story wasn't interesting enough to be included.'

'But I did end up with an amazing tapestry with a little bit of everything.'

A purple dye murex specimen

The purple dye murex, Bolinus brandaris, was once a crucial component in a fabric dye called Tyrian purple, thought to have first been used more than 2,000 years ago. It took thousands of shells to make even a tiny amount of this expensive dye and it became a status symbol, with only those of the highest ranks allowed to use it for their garments.

A collection of money cowries

These shells are money cowries, Monetaria moneta. Until the end of the Roman Empire, around 500 AD, they were widely used as currency - and even remained in use until the twentieth century in some places. 

A queen conch specimen

In Mesoamerica, the queen conch, Aliger gigas, was once used as hand protection in combat, with the shell acting like boxing gloves or knuckle dusters.

Andreia says 'One of the coolest moments was when I was watching QI and they mentioned this story about this shell, which I'd never heard about before, and I knew it had to be in the book.'

Picking favourites

Andreia was a curator of shells long before it became her job at the Museum, spending her childhood collecting and cataloguing shells as a hobby. So it's perfect that her favourite of the 121 stories is that of a shell that also curates its own little collection.

'The carrier shell is beautiful, and it photographs so well,' says Andreia.

'As it builds its shell, it incorporates objects from around it. The one in the book has incorporated other gastropods and sponges - it has a collection, like a mini museum of curiosities, that it carries with it all the time.'

'There are others in the collection that have pebbles or bivalves. But increasingly, because of pollution, you also see them with glass, plastic, metal and other man-made objects.'

A birds-eye view of a carrier shell

There are a few theories as to why the carrier shell, Xenophora pallidula, might collect things. It could be for camouflage, protection or increasing the strength of its shell.

A side-on view of a carrier shell

A side-on view of a carrier shell

Rare shells

While today you might not see shells fetching as much at auction as dinosaur skeletons, they were once a hot commodity.

It's thought that Vermeer's Woman Reading a Letter - now a priceless painting - might have once sold for less at auction than a Glory of the Sea specimen. Then there's the story of a collector who allegedly purchased a second Glory of the Sea only to crush the shell so they could preserve the value of the first.

'Some shells were unique objects,' explains Andreia. 'That's mainly because they didn’t know where they lived, or they lived very deep and there were no techniques to be able to collect them.'

'They were so rare that there were lists of all the existing ones. And when one went up for auction there were bidding wars that reached thousands of pounds.'

For example, one such list published in 1966 listed only 41 specimens of Glory of the Sea. These shells sold for vast sums.

A Glory of the Sea specimen

Though Glory of the Seas, Conus gloriamaris, are considerably less rare and expensive than they once were, they are still highly prized by collectors, despite there now being thousands of shells known.

A precious wentletrap specimen

A precious wentletrap, Epitonium scalare, would once have sold for hundreds of pounds. They were so rare and in demand that counterfeit shells were created and sold. 

A brown sea silk glove

This glove from the 1700s was made from sea silk - long threads, also known as byssus, that pen shells use to anchor themselves to the sand.

Other shells, such as the precious wentletrap, were so in demand that fake specimens are thought to have been created and sold.

'The legend is that they were counterfeited by using rice flour, and that when people put them into water to wash them, they dissolved.'

'As far as I know, we don't have one of these fake shells in the collection, but maybe we had one back in the day.'

Though there are still shells today that are very valuable and that collectors will pay a lot of money for, times have changed. Some shells, particularly land snails, are now protected by CITES regulations, which seek to ensure that the trade of a species doesn't threaten its survival – although it is possible that some illegal trade may still take place.

While shells themselves may be precious, so too are items derived from them, such as sea silk gloves made from the thread of pen shells or the carved nautilus shell currently on display in the Treasures Gallery.

A miraculous diplomat snail shell

Don't let the picture fool you. This is the shell of a miraculous diplomat snail, Plectostoma mirabile, and at only about three millimetres tall it's almost invisible to the naked eye. These molluscs are found in the rainforests of northern Borneo and are at high risk of extinction due to human activities. 

A green tree snail shell

Demand for the green tree snail, Papustyla pulcherrima, grew from the 1930s onwards, particularly for use in jewellery. Combined with habitat destruction, this has meant that these snails are now endangered and are currently protected by CITES regulations.

Collecting shells

Picking up a shell at the beach is not uncommon, and many of us have one or two as holiday mementos dotted around our homes. But it's important to be mindful of the rules in the area you're visiting, as some shells are protected by law.

'It's a very different thing collecting something on the British coastline to picking up a shell and trying to bring it home from a trip to the Philippines or Australia,' Andreia explains.

What might be a surprise is that while the animal that built the shell might have died a long time prior, the legislation that governs whether you can collect, import or export the empty casing is effectively the same as for the living animal, even if you didn't kill the animal in order to collect its shell.

In some places, the best advice when deliberating whether or not to collect a shell, is that it's simply best not to, and that's not just from a legal viewpoint.

'When I went to Yosemite National Park in America, we were asked not to collect anything. Not a stick, not a stone, not a flower. Leave everything because if you enjoyed it then the next person can enjoy it too. Maybe that's a good approach for shells as well,' Andreia suggests. 

An Eloise's acteon specimen

Eloise's acteon gives its name to Eloise Beach on Masirah Island off the east coast of Oman. It was once commonly found there, but has become rare in recent years, potentially due to being over collected. 

From brilliant and bizarre biology to unusual uses, endangered species and quirky Museum stories, Interesting Shells has it all.

Andreia says, 'I work with seashells all the time, but for me, the best thing about this book is that I still learned so much, especially about land snails, which I don't usually work with.'

'I'm very grateful to my colleagues for spending time chatting with me about their work and also to our photographer Kevin Webb.'

Are you hooked? Grab yourself a copy of Interesting Shells from the Museum's online shop