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.
A carbon-zinc D battery, positive terminal up. D cell batteries. A D battery (D cell or IEC R20) is a size of dry cell. A D cell is cylindrical with an electrical contact at each end; the positive end has a nub or bump.