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 been formed in the following manner. Bead blanks were first formed from the raw shell followed by perforation by use of a drill with what is proposed to be a bow or pump drill. The blanks are then attached to a string and specific appliqués were added to complete the shell beads. What these latter shell beads tell us is that there was indeed a high level of technique around the time that these shell beads were being made. A specific set of developed tools, specific processes and a very concise plan are required to form these beads. Mere selection