What eats rocks?
All birds eat gravel and small stones to help them digest their food. The rocks, stones or gravel go into the “gizzard,” a part of the bird’s digestive system where food is ground into smaller pieces. The stones move around in the gizzard and do the grinding. Gizzard stones are also called “stomach stones” and “gastroliths.”
Some reptiles such as crocodiles also eat rocks to use as gizzard stones.
Some dinosaurs used to eat rocks too—and for the same purpose that birds still eat them today.