A horn-shaped vessel, typically made from pottery or metal, with a hole at the bottom used for pouring wine. Rhyta (pl.) were used at elite banquets and for pouring offerings to the gods (libations). Rhyta frequently represent the heads of humans, animals or mythological creatures.Web resource here. Videos here and here.
Ram-head rhyton by the Brygos Painter. Ca. 480-470 BCE. Cleveland Museum of Art.