The ceramics of the Iron Age take on many diverse forms. Unlike the previous period, when clay objects were hand built, the Iron Age saw the introduction of the potter's wheel. Changes in mortuary practices were also partially responsible for new kinds of ritual vessels that may reflect the influence of material culture of the Chinese Han dynasty (206 BC–AD 220). In particular, objects raised on a foot or pedestal appear relatively suddenly in Korea, although such footed vessels had already been used in Bronze Age China. The earliest extant sculptural forms also date from this period, as seen in this imposing bird-shaped vessel of the second to third century. Such objects may represent tribal totems or specific beliefs in the afterlife. Made of a soft, low-fired clay, they are clearly distinguishable from the more utilitarian pots found in great quantities at residential sites.