The Five-Year-Old, putting on her favorite pearl necklace on a recent Sunday morning: “Mommyo, did you know pearls are mummified parasites?”
The Five-Year-Old: “Yep. Just ask the iPhone.”
And so I did.
And what do you know — she’s right, mostly. Naturally occurring pearls are not the result of random bits of grit making their way into an oyster’s mouth–most of the time the oyster just spits those out–but rather a mollusk’s way of defending against drilling worms and wayward food particles that become trapped in its shell. Since the mollusk can’t simply eject the particle, the affected oyster, clam or mussel coats it with layers of aragonite and conchiolin — the same two substances it uses to create its own shell. Over time the coating transforms the icky invader into a pearl prized by collectors around the world.
As you might have guessed, this is pretty much the same process used to create cultivated pearls, with the exception that the round bead or scrap of shell triggering the coating process is implanted by human hands, not laid by random chance. (Naturally occurring pearls are quite rare, with only 1 in 10,000 mollusks ever creating one.)