The stomach of a crocodile is a rocky place to be, for more than one reason. To begin with, a croc’s digestive system encounters everything from turtles, fish and birds to giraffes, buffaloes, lions and even (when defending territory) other crocodiles. In addition to that bellyful-o’-ecosystem, rocks show up too. The reptiles swallow large stones that stay permanently in their bellies. It’s been suggested these are used for ballast in diving.