How does a cownose stingray, with no bones in its jaws, chomp on hard-shelled prey such as mussels and snails? In the same way a fossilized animal becomes hard as rock: with minerals, reports biologist Adam Summers of the University of Massachusetts at Amherst. The stingray, however, somehow deposits the minerals as a strong coating around its jaws and into columns that act as reinforcing struts within its jaw cartilage for crushing hard prey. Summers´ discovery marks the first time an animal has been found using mineralization deep in its cartilage for structural purposes.