The world’s strongest natural material: snail teeth

Rebecca Su | Mar. 26, 2015

The limpet, a humble aquatic snail no longer than a thumb, spends most of its life clinging to a single patch of rock. To help it stick better, it carves out a small indent for itself, which scientists call a home scar. It moves occasionally to graze on algae, leaving trails of slime in its wake so it knows how to get back.

It’s not much at first glance, but it turns out that the limpet has been keeping a remarkable secret: its teeth, well-adapted to scraping algae off of rocks, are the strongest known biological material on earth.

In February, researchers at the University of Portsmouth found that limpet teeth have a tensile strength of up to 6.5 GPa. The previous frontrunner was spider silk, which has applications ranging from bullet-proof vests to medical devices; its tensile strength is only 4.5 GPa.

The team found that the key ingredient in limpet teeth is a tough mineral called goethite. The strength comes not only from the goethite’s chemical makeup, but also from its structure: in limpet teeth, goethite is drawn out into fibers ten thousand times thinner than a human hair, which reinforce the soft protein in the tooth. And while the strength of most materials decreases with size — think about how a large cookie breaks easily, but those tiny crumbs keep their shape — limpet teeth remain just as strong at any size.

Studying the unique structure of the limpet’s teeth can teach scientists to design stronger materials. Applications range from dental restorations to boat hulls — anything that needs to be strong, lightweight, and resistant to wear and tear.

Rebecca Su is a junior in Silliman College. Contact her at rebecca.su@yale.edu.

(Featured image courtesy of Asa Barber, University of Portsmouth.)