Fossil brittle star from the Ordovician

Brittle star from Morocco

In the south of Morocco, there are a number of formations where brittle stars (ophiuroids) are found. The best known sites are the Tiourine formation and the Kataoua area. These fossils are among the oldest ever found and date back to the Ordovician (485 to 443 million years old). The orange colour is natural and caused by iron oxidation.

Starfish or brittle star?

The fossil starfish and brittle star from Morocco are among the oldest fossils on earth. It is especially remarkable that both animals are still living in our oceans and seas in almost unchanged form! The two animals are closely related and the difference lies mainly in their shape. Starfish can have between five and forty arms, whereas brittle stars always have five. The arms of the starfish pass into the central body, while the arms of the brittle star are attached to a central part. Both have calcite legs that form a skeletal structure. However with the starfish these are fused together, while the arms of the brittle star are independent of each other.