1) Digestive system component 
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith`s role in digestion. Other species use gastroliths as....
stone ingested by an animal to aid in digestion
• (n.) See Crab`s eyes, under Crab.
(from the article `dinosaur`) ...unusual bacterial population in the intestines to break down the fibre. A digestive tract with one or more crop chambers containing stones might ...
(gas´tro-lith) a calculus in the stomach; called also gastric calculus.
Gas`tro·lith noun [ Gastro- + -lith .] (Zoology) See Crab's eyes , under Crab . 
Type: Term Pronunciation: gas′trō-lith Definitions: 1. A concretion in the stomach. Synonyms: gastric calculus
In pathology, a gastrolith is a stone in the stomach.
Stone that was once part of the digestive system of a dinosaur or other extinct animal. Rock fragments were swallowed to assist in the grinding process in the dinosaur digestive tract, much as some birds now swallow grit and pebbles to grind food in their crop. Once the animal has decayed, smooth round stones remain – often the only clue to th......