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
Powder glass beads imitating coral, blue beads were also highly valued. "Keta awuazi beads", originating from Nigeria or possibly Togo, were made in horizontal molds and mold marks are often evident along their sides. Keta awuazi beads are cylindrical in shape. Manufacture ceased during the 1940s. Krobo bead makers produced similar blue powder glass beads, using glass derived from cold cream jars to achieve the blue colouration. Mauritanian Kiffa beads are also manufactured through the wet core technique. Glass, which is finely crushed to a powder, is mixed with a binder such as saliva or gum arabic diluted in water. Decorations are made