Crocodile bulks of swallowed prey flesh and bone. Many large crocodilians swallow stones (called gastroliths or stomach stones), which may act as ballast to balance their bodies or assist in crushing food, similar to grit ingested by birds. Herodotus claimed that Nile crocodiles had a symbiotic relationship with certain birds, such as the Egyptian plover, which enter the crocodile's mouth and pick leeches feeding on the crocodile's blood; with no evidence of this interaction actually occurring in any crocodile species, it is most likely mythical or allegorical fiction. Since they feed by grabbing and holding onto their prey, they have evolved
Egyptian plover black marking are intermixed with brown. The Egyptian plover is a localised resident in tropical sub-Saharan Africa. It breeds on sandbars in very large rivers. This usually very tame bird is found in pairs or small groups near water. It feeds by pecking for insects. The call is a high-pitched "krrr-krrr-krrr". Its two or three eggs are not incubated, but are buried in warm sand, temperature control being achieved by the adult sitting on the eggs with a water-soaked belly to cool them. If the adult leaves the nest, it smooths sand over the eggs, though if it is frightened