Orthoceras fossil plates consist of multiple fossil nautiloids on a fossil marble bedrock approximately 400 million years old. Each orthoceras fossil nautiloid is carved out from the background bedrock and the whole plate is polished to bring out the markings in the fossil marble.The name Orthoceras, means “straight horn” which refers to it’s characteristically long straight conical shell. Othoceras nautiloids are a genus of the extinct nautiloid cephalopod. These ancient ancestors of the squid ranged in size from less than a centimeter to more than a metre. The shape and segments of the shell that housed the soft body of the organism which resided in the shell opening segment, are a result of the creature constantly outgrowing its shell, resulting in a new shell segment larger than the one before. The shell is all that remains in the fossil record, and the distinctive segments with their divisions called septa can clearly be seen in the fossil markings.