Talk:Pearl/@comment-26136291-20141005011736/@comment-16722520-20141014190011

Pearl are made by clams or oysters. Pearls start out as a small undigestible(to the clam or oyster) "object", this "object" can be a small organism (though less likely), but is in most cases indeed a grain of sand. To reform the object to a pearl the clam places something called (very fittingly) "mother-of-pearl" or "nacre". This substance is a "glue" that hardens out. The nacre is created by the oyster for one purpose only, this purpose being glueing it to foreign objects and the inside of its shell. The reasoning behind this being that if something is nacred, it becomes soft and round thus less likely to hurt the oyster.