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) been inspired by the name Margaret, which means "pearl". In Nathaniel Hawthorne's 1850 novel "The Scarlet Letter", heroine Hester Prynne names her illegitimate daughter Pearl because the child is "of great price, purchased with all she had, her mother's only treasure." The passage refers to the Parable of the Pearl in the New Testament. The gates to Heaven are also commonly pictured as made of pearl. It was among the 50 most popular names for girls born in the United States between 1880 and 1911, remained among the top 100 most popular names for girls between 1911 and 1926 and