Both marble and bronze are easy to form and very durable; as in most ancient cultures there were no doubt also traditions of sculpture in wood about which we know very little, other than acrolithic sculptures, usually large, with the head and exposed flesh parts in marble but the clothed parts in wood. As bronze always had a significant scrap value very few original bronzes have survived, though in recent years marine archaeology or trawling has added a few spectacular finds, such as the Artemision Bronze and Riace bronzes, which have significantly extended modern understanding. Many copies of the Roman period are marble versions of works originally in bronze. Ordinary limestone was used in the Archaic period, but thereafter, except in areas of modern Italy with no local marble, only for architectural sculpture and decoration. Plaster or stucco was sometimes used for the hair only.