Wiwaxia somewhat resembles a very small porcupine (about 30 mm in diameter) with its quills pulled out. The body is covered by both spines and scales. The spines are believed to have been used for defence purposes. Wiwaxia probably grazed or scavenged by walking or crawling along the sediment. One hundred and forty specimens are known from the Burgess Shale. Similar scales and spines have turned up in similarly aged sediments from elsewhere around the world suggesting that Wiwaxia was widespread during the Cambrian.