An ancient Chinese jade artifact. The earliest cong (pl.) were produced by the Neolithic Liangzhu culture. Later examples date from the Shang (ca. 1500-1050 BCE) and Zhou (1050-221 BCE) dynasties. In form, a cong is a hollow cylinder embedded in a  rectangular block. Proportions vary: some cong are squat,  others are taller than they are wide. The outer surfaces are sometimes decorated with mask-like faces. Although generally considered to be ritual objects, the original function of the cong is unknown. Web resource here.

Jade Cong. Liangzhu Culture. Ca. 2500 BCE. Private Collection.