* Irritation is Key: A pearl forms when an irritant, such as a parasite or a piece of grit, enters the oyster's soft tissue.
* Nacre Deposition: The oyster's defense mechanism kicks in. It begins to coat the irritant with layers of nacre, also known as mother-of-pearl. Nacre is a substance made of calcium carbonate and conchiolin, the same material that lines the oyster's shell.
* Layer Upon Layer: The oyster continues to deposit layers of nacre around the irritant. Over time, these layers build up to form a pearl.
* Patience is a Virtue: The process can take several years, depending on the type of oyster, the size of the irritant, and environmental factors.
So, in short, pearls are created by oysters coating an irritant with layers of nacre over a long period of time.