Cultured pearl is calcium carbonate and a fibrous protein called conchiolin. As the nacre builds up in layers of minute aragonite tablets, it fills the growing pearl sac and eventually forms a pearl. Natural pearls are formed by nature, more or less by chance. On the other hand, cultured pearls are human creations formed by inserting a tissue graft from a donor oyster, upon which a pearl sac forms, and the inner side precipitates calcium carbonate, in the form of nacre or "mother-of-pearl". The most popular and effective method for creating cultured pearls are made from the shells of freshwater river mussels
Pearl Krabs Grandma's Apron, a store for elderly residents on the ground floor of the shopping center. Beatrice, her boss at Grandma's Apron, is voiced by actress Betty White. The disparity in species between Pearl and her father has never been explained directly in an episode, but merchandise makers and production crew members have stated that Mr. Krabs was once married to a whale who gave birth to Pearl. A trivia book penned by former "SpongeBob" writer David Fain in 2000 states that Pearl "takes after her mother," implying that she is the biological offspring of Mr. Krabs and a whale. According