Where would you find pearls?

Pearls come from molluscs--a group of animals which includes squids,clams, and oysters. Under its shell the mollusc has a mantle, or outer-skin. When a particle of dirt, or tiny marine creature gets stuck in this mantle, a hard substance forms around it. This makes the pearl. It is formed of the same material as the mollusc shell--nacre or mother-of-pearl.