The domed, oval shaped disks used as jewelry pieces in a typical Native American belt, commonly called a concho belt.
The controversy over the spelling of this item is ridiculous since nobody sees the form of a shell in these round or oval, usually domed discs. One writer insists the form comes from the Plains Tribes who strung graduated sets of the discs as a decoration called a trailer. Obviously discs as decorations have a very ancient pedigree. General usage favors concho.