A pearl  is a  hard, glistening object produced within the soft tissue (specifically  the mantle) of a living shelled mollusk or another animal, such as  fossil conulariids. . Cultured or farmed pearls  from pearl  oysters and freshwater mussels make up the majority of those currently sold. Pearls  are made   by marine oysters and freshwater mussels as a natural defence against     an irritant such as a parasite entering their shell or damage to their  fragile body. The oyster or mussel slowly secretes layers of aragonite  and conchiolin, materials that also make up its shell.      Pearls  have organic origins. They form within various species of freshwater and saltwater mollusks. Simply put, pearls  are gems but not stones .   Pearls  are the Only Gemstone to Come from a Living Creature. Despite being classified as a gemstone, pearls      differ significantly from all others (including sapphires, rubies,  emeralds, etc.) due to the fact that they are the only gems to com...