Kapkap

From the Minneapolis Institute of Art record

The brown, lace-like discs attached to the white clam shells of these ornaments are made of tortoiseshell. When boiled, tortoiseshell becomes pliable and can be cut into patterns. The marble-like shell of the giant clam is a technically challenging medium, nearly as hard as stone. The art of working it reached a peak on the Solomon Islands in Oceania. The ornaments, called kapkap , were used as exchange goods throughout the region, and are still worn today at festivals, signifying personal wealth and status. Papua New Guinea