Orthocones and Orthoceras

An orthocone is a type of extinct marine creature known as a cephalopod, which is a group of mollusks that includes squids, octopuses, and nautiluses.

Orthocones are characterized by their long, cone shaped shells, which were composed of calcium carbonate and often fossilise in some areas – with a large amount coming from Morocco, often cut and polished to make decorative objects.

Orthocones were long, straight-shelled sea creatures that lived a very long time ago. They were part of a group called cephalopods, which also includes modern animals like squids and octopuses.

Orthoceras is the name that historically was given to all orthocones, and often still is, meaning most things sold as ‘othoceras’ are not.

These animals lived in the oceans hundreds of millions of years ago, from the late Cambrian to the late Triassic – but they were most common in the early Paleozoic.

The word “orthocone” means “straight cone,” which describes the shape of their shells. Unlike modern squids, which have soft bodies, orthocones had hard outer shells. These shells were long and cone-shaped, divided into chambers.

Fossil orthocones are quite common and are often found in limestone rocks. Their fossils look like long, pointed tubes, sometimes with lines across them that show the chambers. These fossils can be very beautiful and are sometimes used in jewellery or decorative stone – particularly in the case of the ‘fossilstone marble’ from the High Atlas.

Scientists believe that Orthocones moved by squirting water out of its body, like modern squids do. It probably used its tentacles to catch small animals to eat.

Further reading