An amphora (English plural: amphorae or amphoras) is a type of container of a characteristic shape and size, descending from at least as early as the Neolithic Period. Amphorae were used in vast numbers for the transport and storage of various products, both liquid and dry, but mostly for wine. It is most often ceramic, but examples in metals and other materials have been found. Stoppers of perishable materials, which have rarely survived, were used to seal the contents. Two principal types of amphorae existed: the neck amphora, in which the neck and body meet at a sharp angle; and the one-piece amphora, in which the neck and body form a continuous curve. Neck amphorae were commonly used in the early history of ancient Greece, but were gradually replaced by the one-piece type from around the 7th century BCE.