shell

Pearl is a secretion formed inside the heart of a spherical shell of some types of shellfish and oysters are used as a cornerstone cream.

Produce such material from cells of epithelial (in the fold or lobe or cloves in the wall lining the shell of mollusks tissue   circular of coincidence, the body, and excreted in the layers of a sequence on the body of annoying are usually parasites in the case of natural pearls hanging in the soft tissue of the oyster

Pearl built from layers of Alerjohnat or calcite crystalline carbonate Alcaliswm and hold the layers together conchiolin material (organic substance horny cortical solid and installed similar to the installation of mother of pearl which forms the inner layer of oyster shell ·

Precious pearls are obtained from the shellfish saltwater especially the kind of Pinctata as well as shells fresh water especially the kind of Hyriopsis and the largest center for pearls natural world in the Persian Gulf, which is said to produce the best pearls salt water and there are important sources, among other coasts of India and China , Japan, Australia and various Pacific islands, Venezuela and Central America and the rivers of Europe and North America, in ancient times the Red Sea was an important source of pearling ·