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.
Vitamin D is fat-soluble vitamin that is needed to be healthy and maintain strong bones. Known as the sunshine vitamin, vitamin D is formed when skin is exposed to the sun's ultraviolet rays and is also found in dietary supplements and certain foods.