This is just one example of Orthoceras Fossils available. Prices start at $30.00. Orthoceras are extinct members of the Cephalopod class. These primative sea creatures are similar to the modern chambered nautilus, but grew a straight shell rather than a coiled one. Now extinct, the 345 - 395 million year old Devonian age orthoceras, meaning "straight horn", is an ancestor of the squid and octopus. If you have questions, please contact: rscustomerservice@gmail.com. We offer a variety of custom home decor pieces such as laser etching, custom cut stone, and address plaques. Contact us to personalize a pet memorial, or garden marker. They make great gifts!