Patella

1. A small dish, pan, or vase.
2. (Anat.) The kneecap; the kneepan; the cap of the knee.
3. (Zoöl.) A genus of marine gastropods, including many species of limpets. The shell has the form of a flattened cone. The common European limpet (Patella vulgata) is largely used for food.
4. (Bot.) A kind of apothecium in lichens, which is orbicular, flat, and sessile, and has a special rim not a part of the thallus.