Many small animals grow their teeth, claws and other “tools” out of materials that are filled with zinc, bromine and manganese, reaching up to 20% of the material’s weight. My colleagues and I call these “heavy element biomaterials,” and in a new paper , we suggest that these materials make it possible for animals to grow scalpel-sharp and precisely shaped tools that are resistant to breaking, deformation and wear. Because of the small size of things like ant teeth, it has been hard for biologists to test how well the materials they are made of resist fractures, impacts and abrasions. My research group developed machines and methods to test these and other properties , and along with our collaborators, we studied their composition and molecular structure . We examined ant mandible teeth and found that they are a smooth mix of proteins and zinc , with single zinc atoms attached to about a quarter of the amino acid units that make up the proteins forming the teeth.…