진주조개속, commonly known as pearl, refers to a group of mollusks that produce pearls. These marine creatures are typically found in oysters and mussels, where they create pearls as a defense mechanism against irritants. The process involves secreting layers of nacre, a substance that coats the irritant, eventually forming a pearl. The value of pearls varies based on factors such as size, shape, color, and luster. Cultured pearls are produced through human intervention, where a small bead is inserted into the mollusk to stimulate pearl formation. Natural pearls, on the other hand, occur without human assistance and are rarer, making them more valuable.