Sea snail teeth set record as world's strongest material

PORTSMOUTH, England, Feb. 18 (UPI) -- A series of strength tests and microscopic investigations brings a new revelation for the world's strongest material: It's sea snail teeth.

The natural composite material that forms the teeth of limpets -- "limpet" is the informal name for all aquatic snails -- is the strongest in the world. Researchers at the University of Portsmouth, in the south of England, confirmed as much after using atomic force microscopy to test the small-scale mechanical behavior of the teeth.

"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," said study leader Asa Barber, a professor at the university's School of Engineering. "But now we have discovered that limpet teeth exhibit a strength that is potentially higher."

The atomic force microscope used to test the teeth pulls each end of a piece of the tooth material in opposite directions until it snaps. The device renders the material strength as a measurement of gigapascals (GPa).

"One of my colleagues on the paper, from Italy, found some exotic spider silk that was about 4.5GPa, and we measured about 5GPa," Barber told BBC News.

It makes sense that snail teeth would have to be remarkably durable, as they're needed to scrape algae from the surface of cragged coastal rocks. Scientists found that the secret to snail teeths' remarkable strength and durability is the presence of goethite.

Goethite is an iron-bearing hydroxide mineral. Extremely hard needle-like goethite crystals form inside the snail's teeth as they grow.

"Limpets need high-strength teeth to rasp over rock surfaces and remove algae for feeding when the tide is in," Barber said. "We discovered that the fibers of goethite are just the right size to make up a resilient composite structure."

Researcher say the composite structure of the limpet teeth could be replicated in the engineering of material for contact-prone components -- like cars, boat hulls and aircraft structures.

The new study was published Wednesday in the Royal Society journal Interface.