The oysters are nucleated with a bead composed of mother-of-pearl and a small piece of mantle tissue. This bead becomes the nucleus of the pearl and is the reason akoya pearls are more often perfectly round.
Carbon definition, Chemistry. a widely distributed element that forms organic compounds in combination with hydrogen, oxygen, etc., and that occurs in a pure state as diamond and graphite, and in an impure state as charcoal.
Carbon (C) is a chemical element that, when burned with oxygen (O 2), combines to make carbon dioxide (CO 2). It is found in all organic materials whether alive or dead. Carbon is released as CO 2 when we burn fossil fuels such as coal, oil and gas. It is also produced when animals and plants use oxygen to release energy from food or when they die. Most of our atmosphere is made up of nitrogen (78 per cent by volume) and oxygen (21 per cent by volume).