Olive shells (Olivella biplicata), called mutū'gu (P, N), kolo'asi (C), lū'kkū (C), were obtained, at least in part, from Monterey bay. The Costanoan inhabitants of its shores allowed the Miwok to make journeys thither to procure these shells. The Miwok did not appreciate the lustrous grays, browns, and whites of the living shells, and proceeded to destroy the luster and to whiten the shells by gently baking them in the ashes of a fire made of buckeye wood and white oak bark, after which they were sifted from the ashes in an openwork basket. Care was taken constantly to turn the shells lest they burn to an unpleasing brown. Any other wood fire was said to have that effect. A smaller shell, called ka'ssutu (C), perhaps also an Olivella, was similarly treated.

The tip of the spire of the olive shell was ground off, so as to leave an aperture for stringing (plates LXIII, fig. 4, and plate LXVI). A string of shells one reach (ana, C) in length was worth one dollar. The ana was the customary unit of measure for strings of these shells. Such strings of whole olive shells were used for money as well as ornament. As ornaments they were draped around the neck and over the chest, worn as belts, and tied on as headbands.

For olive shell ropes (plate LXVI) the shells with spire tips ground off were threaded on two strings of requisite length. The two strings of shells were laid together so that the shells were in pairs side by side. Then the strings were laced together with string (worsted in two modern examples), the resulting fabric being a tiny triangular bit of tapestry between the aperture of each pair of shells, the base of the triangle being always at the base of the shells. The weft element is continued downward between the next pair of shells to form there the next tiny triangle of tapestry. Each little triangle is secured by a half hitch of the weft element before it proceeds downward between the next pair of shells. This half hitch serves also the purpose of throwing the weft element to the center, where it is hidden from view between the next two shells. The plate reveals that, although the shells are arranged aperture to aperture, the lips of the shells of one row always turn down, the lips of the other row always up, as one looks at one side of the rope.

The short cords which terminate the shell ropes are formed of tapestry lacing in one example (1-10162) and of three-strand braid in the other example (plate LXVI). The former rope is nearly twenty-four feet long.