Answer:
A natural pearl (often called an Oriental pearl) forms when an irritant works its way into a particular species of oyster, mussel, or clam. As a defense mechanism, the mollusk secretes a fluid to coat the irritant. Layer upon layer of this coating is deposited on the irritant until a lustrous pearl is formed.
Step-by-step explanation:
Instead, a pearl forms when an irritant such as a wayward food particle becomes trapped in the mollusk. The animal senses the object and coats it with layers of aragonite ("ah-RAG-uh-nite") and conchiolin ( "KON-kee-uh-lin"). These two materials are the same substances the animal uses to build its shell.