Why shells spiral

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.