A WHOLE NEW WHORL

MANY OF US HAVE SEEN SEASHELLS ON THE BEACH AND MARVELLED AT THEIR COLOURS, AND PATTERNS OF CURVES AND RIDGES. BUT SEASHELLS ARE FAR MORE THAN JUST PRETTY OBJECTS, AND THEIR INTRICATE STRUCTURES CAN HELP US LEARN MORE ABOUT THE INHABITANTS THAT ONCE DWELLED INSIDE THEM

- DR HELEN SCALES

PURPLE STAIN

ABALONE

Abalone shells are gleaming and shiny on the inside, thanks to layers of nacre, the same stuff that pearls are made of. Nacre is 95 per cent calcium carbonate – chalk, essentially – but try dropping an abalone shell and you’ll see it’s virtually shatterproof. This super strength comes down to nacre’s microscopic structure of diamond-shaped crystals stacked like bricks, with layers of chitin in between. Chitin is the same tough protein that makes insect exoskeletons and shrimp shells. If the outside of the shell gets damaged, the inner nacre layer stops cracks from growing bigger. The nacreous crystals slide over one another and the chitin stretches, dampening the energy of a spreading crack and halting it in its tracks.

Scientists from Canada’s McGill University recently mimicked the structure of nacre using glass flakes and acrylic to produce a transparent composite that’s three times stronger than normal glass and five times more resistant to fractures. Easy and cheap to make, this could be the ideal material for the next generation of smartphone screens that won’t smash no matter how hard they’re dropped, all inspired by nature’s nacre.

BUOYANCY AID

CHAMBERED NAUTILUS

This is the view inside the shell of a chambered nautilus that’s been sliced into two halves, left and right. When the nautilus was alive, each of those chambers was filled with gas, which turned the shell into a buoyancy device. The floaty shell helps a nautilus to hover in the water column and therefore save energy.