Mother-of-pearl is a natural material that is created by some mollusks, such as oysters and abalone. It is composed of calcium carbonate in the form of aragonite and conchiolin, which is a protein substance. The term 'mother-of-pearl' is derived from its French name, NACRE, which means 'mother of pearl.' NACRE is the iridescent material that lines the inside of the shells of certain mollusks, and it is also known as 'pearly mother-of-pearl.' Oysters are the most common source of mother-of-pearl, but it can also be found in other mollusks, such as abalone.