Search results
Results from the WOW.Com Content Network
The iridescent nacre inside a nautilus shell Nacreous shell worked into a decorative object. Nacre (/ ˈ n eɪ k ər / NAY-kər, also / ˈ n æ k r ə / NAK-rə), [1] also known as mother-of-pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed.
Abalone shells and associated materials, like their claw-like pearls and nacre, have been used as jewelry and for buttons, buckles, and inlay. [ 15 ] [ 16 ] [ 17 ] These shells have been found in archaeological sites around the world, ranging from 100,000-year-old deposits at Blombos Cave in South Africa to historic Chinese abalone middens on ...
The various species of Pinctada produce different maximum sizes and colors of pearls, depending on the size of the species and the natural color of the nacre inside the shell. Black South Sea pearls, or Tahitian pearls come from the black-lip oyster; gold and silver South Sea pearls from the gold-lip and silver-lip oysters; and Akoya cultured ...
Pāua shells are frequently used to represent eyes of human and animal figures in Māori carvings, and used as decorations on skirts, cloaks and in earrings. [8] Pāua is traditionally are associated with the stars or whetū , the symbolic eyes of ancestors that gaze down from the night sky.
The outermost layer is the periostracum which is resistant to abrasion and provides most shell coloration. The body of the snail contacts the innermost smooth layer that may be composed of mother-of-pearl or shell nacre, a dense horizontally packed form of conchiolin, which is layered upon the periostracum as the snail grows. [citation needed]
The exterior of the shell is striated and dull. The color of the shell is very variable from species to species, which may reflect the animal's diet. [6] The iridescent nacre that lines the inside of the shell varies in color from silvery white, to pink, red and green-red, to deep blue, green to purple. The animal shows fimbriated head-lobes.
The shell has a rounded outline, with a nearly equal height and width. Oyster shells are usually oval or pear-shaped, but will vary widely in form depending on what they attach to. Oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl". An oyster can filter 1.3 gallons of water per hour.
The genes used to control its formation vary greatly between taxa: under 10% of the (non-housekeeping) genes expressed in the shells that produce gastropod nacre are also found in the equivalent shells of bivalves: and most of these shared genes are also found in mineralizing organs in the deuterostome lineage. [6]