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
Wampum eight white or four black wampum equalling one "stuiver", meaning that the white had the same value as the copper duit coin. The colonial government in New Jersey issued a proclamation setting the rate at six white or three black to one penny; this proclamation also applied in Delaware. The black shells were rarer than the white shells and so were worth more, which led people to dye the white and dilute the value of black shells. Robert Beverley, Jr. of Virginia Colony wrote about tribes in Virginia in 1705. He describes "peak" as referring to the white shell bead,