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 wampum was central to establishing and renewing peace between clans and families. When a man representing his respective social unit met another, he would offer one wampum inscribed with mnemonic symbols representing the purpose of the meeting or message. The wampum, thus, facilitated the most essential practices in holding the Iroquois society together. When Europeans came to the Americas, they adopted wampum as money to trade with the native peoples of New England and New York. Wampum was legal tender in New England from 1637 to 1661; it continued as currency in New York until 1673 at the rate of