Pearl or parasite enters a bivalve mollusk and settles inside the shell. The mollusk, irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare. Typically, the build-up of a natural pearl consists of a brown central zone formed by columnar calcium carbonate (usually calcite, sometimes columnar aragonite) and a yellowish to white outer zone consisting of nacre (tabular aragonite). In a pearl cross-section
Pearl (given name) Doll Company in the United States from the 1950s through the 1970s. The doll was based on a cartoon character created by William Steig. One recently named Pearl, the then two-year-old Pearl McKay, was the star of the 2007 short film "The Landlord". Pearl Bailey was an American singer and actress. Pearl Richards Craigie was an Anglo-American novelist and dramatist, who wrote under the pen-name John Oliver Hobbes. Pearl Aday was an American singer-songwriter. Pearl Fryar has a topiary garden described in the documentary film "A Man Named Pearl". Pearl is one of the two members of the fictional band