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, a chemical element that is the basis of all known life and part of the chemical compound carbon dioxide, is the basic currency of the carbon cycle. It is inhaled by sinks to fuel photosynthesis in plant life.