Orthoceras

Extinct class: These very primitive members of the phylum cephalopod are similar to the Ammonite but with a straight shell. Approximately 400 million years old, Orthoceras are the ancestral cousin of the modern squid or octopus. The word Orthoceras means “Straight Horn”, and refers to its shape. All Orthoceras have chambers separated by walls called Septa. They also have a tube that runs down the center of the fossil called a Siphuncle. It is believed that this tube was used to carry air into the chambers to control the buoyancy of the shell. The Orthoceras from Morocco occur as white fossil in a dark gray or black marble matrix. The result is a fossil with very good contrast