This article was originally posted on RealClearScience.

The first person who discovered pearls must have believed he stumbled across a bit of magic. Pull apart the valves of a living oyster, and a beautiful spherical gem of calcium carbonate may lay inside. Alas, it is not magic. A pearl forms in response to tissue damage, such as by the introduction of a foreign body, and the pearl is the oyster’s attempt to wall off the offending object. (A similar process occurs in the lungs of people with tuberculosis.) Today, humans take advantage of this quirk of oyster biology in order to culture pearls on our own terms. Continue reading →