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 tetrachloride, also known as carbon tet or Freon 10, is a chemical compound. Its chemical formula is CCl4. It contains carbon in its +4 oxidation state and chloride ions.