Crocodiles are strictly meat eaters. In the wild, they prefer fish, birds, frogs and crustaceans, but they’re not dainty diners: They grab the prey and crush it with massive jaws, then swallow the meal whole. They’re unable to break off small pieces or chew.
Because of this, a crocodile's digestion requires some help. So a croc will also routinely swallow small stones in order to grind up the food that is sitting in the stomach like a brick. Crocodiles can live for months without eating, due to their slow metabolisms.
Down the hatch, all in one piece:
New meaning to 'kidney stones'...