In addition, all crocodiles are semiaquatic and carnivorous, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as mollusks and crustaceans.

So, sometimes they have to dive into the depths of the ocean to get their food, and because they obviously can’t access a submarine, they can only become one by swallowing some stones. This way they can increase their body weight, as well as their chances of catching bigger meals. These stones are called gastroliths or stomach stones, which line up in their stomach or help in crushing food.