Catalogue entry no. 231 by Max Loehr:
231 Convex Disk or Spinning Whorl
Slightly translucent, variegated greenish gray stone disk, convex on one side and flat on the other. On each side appears a bird figure executed by incised lines and sloping cuts. The bird’s beak, neck, and wing adjoin the perforation concentrically. In the grooves remain traces of cinnabar. Early Western Chou.