Although these circular pendants look like they could be worn as jewelry, they are much too bulky and heavy for such a purpose. Instead, they were likely used in ritual worship of the sky. Bi (pronounced “bee”) disks were made of nephrite, a greenish stone similar to jade. Some were smooth, displaying only traces of the tool marks used to shape them, while others were elaborately decorated. A bi disk from the Zhou dynasty (1100-221 B.C.E.) was discovered in a tomb near Luoyang, China, and is intricately carved with dragons. The ancient Chinese regarded dragons as symbols of power who were thought to pass between heaven and earth and to bring rain. It would have taken many hours of difficult work to grind and polish the dragons and other abstract designs on the Zhou bi disk.