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
Hymn of the Pearl has been preserved and especially treasured in Manichaeism - a version of it appears as part of a north-African Manichaean Psalm book is written in Coptic, called the Psalms of Thomas. The Hymn of the Pearl has also been admired by Orthodox Christian thinkers and members of the Church of Jesus Christ of Latter-Day Saints (Mormons). Please note that wikisource contains the . The "Hymn of the Pearl" is read as part of the narration in Terrence Malick's 2015 film "Knight of Cups". The film deals with themes of pain, loss of direction and transcendence, which are part of the