Disk (<em>bi</em> 璧) with knobs

Perforated disk of the type pi [bi] 璧; bored from both sides, leaving slight median ridge; richly mottled olive greens and tan to golden browns with scattered, lighter, translucent strata, small blackish area near rim on one side only; profuse delicate veinings with earth incrustations; decoration: grain pattern in form of semi circular knobs in high relief between plain beveled margins.