5.4" Cretaceous Fossil Nautilus - Madagascar

This is a 5.4" Nautilus (Nautilidae) from Ambatalafia, Mahajanga Province, Madagascar. This very nice specimen shows the unaltered outer shell along the centerline of the shell and the iridescent inner shell on the sides. There is some damage to the shell that occurred during fossilization.

The shell of a Nautilus is made up of two layers. The inner layer has the iridescent shine while the outer layer provides protection from external forces. Inside the shell are septa which divide the living area of the shell into compartments and help the animal maintain balance and position in the water column.

Nautilus are "living fossils" in that species similar to this one still exist in our oceans.