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) The Pearl (novel) The Pearl is a novella by American author John Steinbeck, first published in 1947. This story is about a poor family which is more likely described as native Americans, who discovers an enormous and valuable pearl. The novella explores man's nature as well as greed, defiance of societal norms, and evil. Steinbeck's inspiration was a Mexican Folk Tale from La Paz, Baja California Sur, Mexico, which he had heard in a visit to the formerly pearl-rich region in 1940. In 1947, it was adapted into a Mexican film named "La perla" and in 1987 into a cult