Yunanocephalus (left) and Wutingaspis tingi (right), Cambrian trilobite fossils. Trilobites were arthropods that fed as they crawled on the seabed. They lived between 500 and 300 million years ago and are now extinct. These specimens date from the Lower Cambrian, and were found in the Chiungussi Formation, 'Chenjiang' Fauna, Kumming, Chenjiang, Eastern Yunnan Province, China. The Wutungaspis on the right is a complete individual; the Yanocephalus on the left is a moult with the librigenes detached. The Yunanocephalus specimen is 0.7 centimetres long. The Wutingaspis specimen is 0.9 centimetres long.