94 THE WEALTH OF THE SEA 



into favor. No one knows when shell beads were first 

 used for ornamental purposes, nor when their use 

 as a medium of exchange became common. 



The chank {Turhinella pyrum), or Indian conch, 

 has been used in India for ornamental and other pur- 

 poses for many, many centuries. Those shells which 

 have the whorl running from right to left are espe- 

 cially prized and are often worth their weight in 

 gold. The Hindus consider the chank sacred, for in 

 their mythology Shankar the Destroyer and Vishnu 

 are pictured as holding a chank shell in one hand; 

 the Buddhist priests have, besides, used these shells 

 as horns for many centuries. 



Abalone or haliotis shells were used for ornamental 

 purposes in China, Japan, New Zealand, and the 

 South Sea islands long before Europeans learned 

 of their beauty and iridescence. 



Nature of Mother-of-Pearl 



Before it is possible to understand the nature of a 

 pearl and appreciate its beauty and color, it is nec- 

 essary to examine the shell of the mollusk in which 

 the pearl was formed. Pearls grow in nearly all 

 bivalves (mollusks with two valves or lateral shells 

 hinged together) and in some univalves, but only 

 those found in mollusks with mother-of-pearl shells 

 are of commercial value. Commercially most of the 

 pearls come either from the so-called pearl-oyster 

 or from certain fresh-water mussels. These mollusks 

 are marvelous creatures which build beautiful, strong 

 houses for themselves out of the water in which they 

 live. The exterior of their habitations is coarse and 



