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
Two Row Wampum Treaty communication across cultural boundaries". Early evidence for wampum in the region indicates that the dominant style was a relatively simple, monochrome design, often with discoidal beads strung together (rather than tubular beads woven together). Historians debate whether or not the technology required to construct the sophisticated two-row style wampum belt (including, most importantly, tubular purple beads) was available to communities in the region prior to 1613; however, Parmenter indicates that archeological evidence does not rule out the possibility that two-row wampum belts may have featured in the initial treaty negotiations between the Dutch and the Haudenosaunee. The significance of the