Orthocerat

Part of speech: noun

Definitions

1. A marine cephalopod from the Paleozoic era characterized by a long, straight, conical shell and a centrally placed siphuncle used for buoyancy control
2. An extinct prehistoric mollusk possessing a slender, tubular shell with internal partitions and a tubular structure running through it for regulating gas and liquid within the shell
3. A fossilized organism identifiable by its elongated, uncoiled shell featuring chambers connected by a central tube that helped maintain stability in ancient ocean waters

Etymology: Its name describes the shell. Greek "orthos" meant "straight" and "keras" meant "horn," so the name means roughly "straight horn." The shells are long, tapering cones that stay nearly straight, unlike the tightly coiled shells of a nautilus. The name comes from the genus Orthoceras, a scientific Latin coinage built from those Greek roots. The English noun takes its form from that genus name. The animal lived in the open chamber at the wide end, and the chambers behind it were filled with gas and liquid, with the siphuncle controlling the flow to help it float.