|(By Hannes Grobe/AWI (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons)|
Mother of pearl, also called nacre, is a combination of "minerals that are secreted by oysters and other mollusks and deposited inside their shells, coating and protecting them from parasites and foreign objects." Nacre is the same substance that builds up and forms around a small particle or irritant that gets inside mollusk to form a pearl. Because the nacre can take up a the whole of a shell's interior, cabochons, with a larger focal area than pearls, can be cut and shaped from the shell.
|Free form faceted mother of pearl cabochons available at TigerBeadStore.com.|
|Just some of the various shapes we carry in Mother of Pearl cabochons.|
(Some of the information for this post was shared from http://jewelry.about.com/od/pearls/qt/motherofpearl.htm)