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
Puka shell and hand-picking these rather uncommon shell fragments from the beach drift. In modern times, beads cut from other types of shell, or even beads of plastic, are used to make imitation puka jewellery. Cone snail shells are sometimes harvested so that they can be chipped and ground down to make more authentic-looking puka jewellery, which is however still not genuine by the standards of the originals. A very glossy patina indicates that the shells in a necklace have been tumble polished. If the edges of the shell beads are chipped, the shells were harvested and manually broken into shape. If