Orthoceras And Blue Topaz Pendant NecklaceBlue Topaz Jewelry This beautiful necklace features an Orthoceras and Blue Topaz set in a sterling silver pendant. Orthoceras, also known as Orthoceratites, is a genus of extinct nautiloid cephalopod. Its name is derived from the words straight horn, referring to its long, conical shell. These creatures roamed the seas during the Ordovician Period (485 million 443 million years ago). They are the ancient ancestors of ammonites and squid that can be