orthoceratite
/ˌɔːθə(ʊ)ˈsɛrətʌɪt/(also orthoceratites) Palaeontology
noun
A fossil shell of a nautiloid cephalod mollusc of the Palaeozoic or early Mesozoic eras, having a long, straight (or nearly straight) chambered shell; specifically a member of the former genus Orthoceratites or family Orthoceratidae; compare orthoceras. Also in Latin form Orthoceratites (in later use only as the name of a genus).
Origin
Mid 18th century; earliest use found in Philosophical Transactions of the Royal Society of London. From post-classical Latin Orthoceratites from ancient Greek ὀρθο- ortho- + κερατ-, κέρας horn + -ίτης -ite.