Acrostolium
An acrostolium (from Gk: akrostolion, ἀκροστόλιον, meaning "high dressing"; also called an aphlaston; ἄφλαστον) or aplustre are the Latin terms that have entered English for a decorative feature found on the sterns of ancient Roman, Greek and other nations' galleys, often as a fan- or tail-like flourish in the upward-curving extension of the ship's rear. It is described in The Oxford Companion to Ships and the Sea as "the symbolical ornament, usually in the form of a shield or helmet, which ancient Greek or Roman ships carried on their prows either to seek favour with the sea gods or to ward off evil.