Where would you find pearls?

Pearls - come from molluscs a group of animals which includes squids, clams, and oysters. Under its shell the molluscs has a mantle, or outer skin. When a particle of dirt, or tiny marine creature gets stuck in his mantle, a hard substance forms around it. This makes the pearl. It is formed of the same materials as the molluscs shell-nacre or mother of pearl. Pearls come in many different shapes and colours. The most valuable ones are completely smooth, spherical and usually white. But there is a black pearl from the Gulf of Mexico, which is also extremely valuable. The people who first discovered how to stimulate the production of pearls were the Chinese. They put the molluscs into the shallow pond, inserted a speck of mud into the mantle, and waited for the pearl to form. After a couple of months they would detach the pearl from the mollusc's mantle and eat the mollusc.