The Channel Islanders created a form of money that was used between
them and in trade with the mainlanders. It was a shell bead money that was a universal form of trade and was made primarily by the island Chumash and Gabrielinos. Made from olivela shells that were broken into small pieces, the shell chips were then drilled with a piece of chert, then strung on twine, and lastly rolled back and forth between hands and a sandstone slab until the edges were even and rounded.
"The standard unit of measure for trade in the Gabrielino
territory and much of Southern California was a string of beads wrapped once around the hand. " from The Gabrielinos
Shells were also worn as jewelry which was a popular trade item. Made
of red or black abalone, clam or olivela shell, the necklaces sometimes were combined with seed or stone beads, or seed pendants.