Shell money most valued by the Native American tribes of the Pacific Coast from Alaska to northwest California was "Dentalium shell", a species of long narrow marine shelled mollusk, a tusk shell or scaphopod. The tusk shell is naturally open at both ends, and can easily be strung on a thread. This shell money was valued by its length rather than the exact number of shells; the "ligua", the highest denomination in their currency, was a length of about 6 inches. Farther south, in central California and southern California, the shell of the olive snail "Olivella biplicata" was used to make beads
Prehistoric beads in the Philippines formed by percussion and grinding. Of the organic shell beads, a small percentage of them are cut shell beads and not all of them were as uniform as the microperforated cut shell beads; the beads that do not display the use of technologically advanced techniques were shells of Tridacna rolled into a barrel shape. The microperforated cut-shell beads are generally less than 2 mm in diameter, and thus appear to require a great amount of effort and technique to produce; these can thus be said to belong to the Metal Age. The microperforated cut shell beads were studied to have