All about Shell

SHELL IS FORMED NATURALLY BY various types of mollusc. Molluscs have calcium rich blood which is filtered through an outer organ called the mantle. The mantle then separates the calcium from the blood and turns it into calcium carbonate crystals which form layers of shell that build up over time. Some types of mollusc shell have an iridescent internal layer known as nacre or mother of pearl which is composed of the same material as pearls.

Coloured shells are created when various pigments within the mollusc’s food are combined with the calcium carbonate crystals and deposited into the outer shell before it hardens. Four main coloured pigments produce the many colours found in shells – yellow, black, green and red. Some shell colours are produced by light refraction off various layers within the shell, such as blue-green or purple