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 is a unique and extra ordinary element produced by burning charcoal. It was officially classified near the end of the eighteenth century. It was merely discovered in the prehistoric times, and the name of the discoverere will probably never be known.