Gallstone

a concretion (hard mass) formed in the gall bladder or bile ducts, composed chiefly of a mixture of cholesterol, calcium bilirubinate, and calcium carbonate, occasionally as a pure stone composed of just one of these substances ( also called biliary calculus or cholelith or chololith)

Description
Gallstones may vary in size and in number. The term silent gallstones signifies gallstones that cause no symptoms.