DoD looks to snails for new armor

The Army and the Department of Defense are funding work on a new type of armor inspired by an unusual snail shell.

Materials scientists realised that the so-called ‘scaly-foot’ snail has a shell unlike any other naturally-occurring or manmade armor, thanks to a unique three-layer structure that dissipates energy.

They believe that it could provide a model for armor for soldiers and vehicles.

The snail lives in a pretty harsh environment on the floor of the Indian Ocean, near hydrothermal vents that spew hot water. It’s exposed to fluctuations in temperature as well as high acidity, and also faces attack from predators such as crabs and other snails.

The crabs are pretty scary predators, grabbing the snails’ shells with their claws and squeezing until they break – which often takes days.

MIT Associate Professor Christine Ortiz and her team measured the force applied to the shell, and the shell’s resulting displacement.

They found that the scaly-foot’s shell was way stronger than most, thanks to a tri-layered structure. It consists of an outer layer embedded with iron sulfide granules, a thick organic middle layer, and a calcified inner layer.

Most other snail shells have a calcified layer with a thin organic coating on the outside.

In the scaly foot gastropod, simulations suggest that the relatively thick organic middle layer can absorb a lot of energy during an attack. It may also help to dissipate the heat variations from hydrothermal vents.

Ortiz plans to carry on on the same theme, looking for inspiration in  natural exoskeletons including those of chitons, urchins, beetles, and armored fish.