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
Pirates of the Caribbean: The Curse of the Black Pearl Jack Sparrow comes to Port Royal to commandeer a ship, and rescues Elizabeth. Norrington identifies Jack as a pirate, and a chase ensues. Jack encounters Will, now a blacksmith and swordsman. They duel, and Jack is captured and imprisoned. That night, the "Black Pearl" attacks Port Royal in search of the medallion. The crew of the "Pearl" capture Elizabeth, taking her to meet Captain Barbossa. Elizabeth claims her last name is Turner to conceal her identity as the governor's daughter. She learns that her medallion is one of the gold pieces that Barbossa's crew took from a treasure of Hernán