Animals That Eat Rocks To Digest

Some animals intentionally swallow stones to survive because they lack teeth for chewing. These stomach rocks, known as gastroliths, act as a makeshift grinder to break down tough food inside the digestive tract.

This practice, called lithophagy, is common in birds like chickens, as well as crocodiles and some seals. Because these animals cannot chew, the rocks churn inside their gizzards to mash up fibrous plants or bones. Some aquatic creatures even use these ingested stones as ballast to help them stay submerged underwater. It is a fascinating biological hack that turns the environment itself into a necessary digestive organ.