Orthoceras is approximately 400 million years old and is a genus of large nautiloids. This Fossil was a straight shelled cephalopod, in the same family as octopus,squid and nautilus. It had a long straight shell with many chambers. The chambers are called septa and the tube running along the back of orthoceras is called the siphuncle.
* Scientific proof may not be available to substantiate these claims.