In contrast to the rare natural pearls that grow accidently, people initiate the growth of cultured pearls by cultivating oysters or mussels with a nucleus to produce pearls. This process requires specific skills. During a tedious and delicate operation, the oyster is briefly opened, the nucleus and a piece of mantel tissue is placed inside then closed again and then put back into the sea. After this operation, nature does its job to produce a pearl, a 2 – 4- year process depending on the kind of mollusc used. Because of seaweed, parasites, and other influences, great efforts must be taken to regularly care for the mussels.