Jade has traditionally been the most highly prized of all materials in China. Owing to its beauty and great durability, it was gradually associated with special powers, particularly protective ones. Over time, it came to be believed that jade would protect the body from decomposition after death. Large numbers of jades were placed in Neolithic graves (around 2500 BC). In the Shang dynasty (about 1500-1050 BC), people wore small animal-shaped pendants. The burial practice of covering the head and, later, the body, with jade pieces originated in the Western Zhou period (1050-771 BC).A later development of that custom, during the Han dynasty (206 BC-AD 220) was the plugging of the corpse's nine orifices with jade. The mouthpiece was often in the shape of a cicada. Jade covers closed the eyes, signifying watchfulness. During the Western Han period (206 BC-AD 9), full jade burial suits appeared.These jade eye covers actually resemble the shape of eyes. The holes at the ends are for attaching the plaques to a cloth or other material. They were also made in glass, a cheap substitute for those who could not afford jade.