A pearl is a beautiful, shiny gem that forms inside the shells of certain mollusks, like oysters and clams. It is created when an irritant, such as a grain of sand, enters the shell. To protect itself, the mollusk secretes layers of a substance called nacre, which eventually builds up and forms a pearl. Pearls come in various colors, shapes, and sizes, making each one unique. People have cherished pearls for centuries, often using them in jewelry like necklaces and earrings. They symbolize elegance and purity, and are sometimes referred to as "the queen of gems." Famous pearls, such as the Pearl of Lao Tzu, have fascinating histories that add to their allure.