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
The Pearl (novel) develops throughout the novel. He begins as a hard-working, simple man that has a wife, Juana, and a son, Coyotito. He is content with his life-style as a diver but is not wealthy until he discovers the pearl. After discovering the pearl, Kino gradually changes to become a completely different man. Though his family is still the center of his actions, he is also driven by greed. Quickly, he becomes obsessed with the material things that the pearl could bring, which is drastically different than before. He is no longer content with his son being uneducated, or his family not