what is a pearl?
http://en.wikipedia.org/wiki/Pearl
A pearl is a hard, spherical object that is produced within the soft tissue of a living shelled mollusk or another type of animal, such as a clam or oyster. It is composed mainly of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. Pearls are prized for their lustrous appearance and are commonly used in jewelry.
To learn more about pearls, you can visit the Wikipedia page dedicated to pearls. The link provided will take you directly to the page, where you can find detailed information about their formation, types, history, and cultural significance.