Sea snail shell the world’s strongest material

By Dominic Harris / AAP 19 February 2015
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The shell of a limpet is the strongest natural material in the world, new research shows

SCIENTISTS BELIEVE THEY may have found the strongest natural material known to man, one that could be copied to make the cars, boats and planes of the future – the teeth of the humble limpet.

Researchers at the University of Portsmouth examined the mechanics of limpet teeth by pulling them apart all the way down to the level of the atom.

They found that the teeth of the snail-like creatures, common to shorelines and rock pools around the world, is potentially stronger than what was previously thought to be the strongest biological material, the silk of a spider.

“Until now we thought that spider silk was the strongest biological material because of its super-strength and potential applications in everything from bullet-proof vests to computer electronics, but now we have discovered that limpet teeth exhibit a strength that is potentially higher,” said Professor Asa Barber, who led the study.

Looking to biology for strong engineering materials

Scientists believe the structure could be reproduced in high-performance engineering, such as racing cars and in boat hulls.

“Nature is a wonderful source of inspiration for structures that have excellent mechanical properties,” Asa said.

“All the things we observe around us, such as trees, the shells of sea creatures and the limpet teeth studied in this work, have evolved to be effective at what they do.

A highly magnified image of limpet teeth. Credit: University of Portsmouth.

Limpet teeth the key to strength

The study, published in the Royal Society journal Interface, found that the teeth contain a hard material known as goethite, which forms in the limpet as it grows.

Limpets need the high-strength teeth to rasp over rock surfaces and remove algae for feed when the tide is in.

“We discovered that the fibres of goethite are just the right size to make up a resilient composite structure,” Asa said.

“This discovery means that the fibrous structures found in limpet teeth could be mimicked and used in high-performance engineering applications such as Formula 1 racing cars, the hulls of boats and aircraft structures.

“Engineers are always interested in making these structures stronger to improve their performance or lighter so they use less material.”

Strong, no matter what their size

Limpets’ teeth were also found to be the same strength, no matter what the size.

“Generally a big structure has lots of flaws and can break more easily than a smaller structure, which has fewer flaws and is stronger,” Asa said.

“The problem is that most structures have to be fairly big, so they’re weaker than we would like. Limpet teeth break this rule as their strength is the same no matter what the size.”

Examining effective designs in nature and then making structures based on these designs is known as ‘bio-inspiration’.