2015 $1 Australian Shell Mother of Pearl 1oz Silver Proof CoinMother of pearl is a hard, smooth, shining iridescent substance that forms the inner layer of the shells of certain molluscs, such as the oyster and abalone. The reverse features a sculpted representation of an Australian white mother of pearl shell with a polished fragment of mother of pearl centrepiece, against a rippled pattern representing the ocean floor. The inscription AUSTRALIAN WHITE MOTHER OF PEARL SHELL and The Perth Mints P mintmark also