6.7" Fossil Nautilus - Madagascar

This is a 6.7" Nautilus (Nautilidae) from Ambatalafia, Mahajanga Province, Madagascar. This specimen has been worn down and now shows inner shell in all but the deepest recesses. There is a small area of damage that occurred during fossilization, near the opening of the shell.

The septa are shell walls that divide the internal area of the shell into compartments. As the animal outgrows the compartment it is living in, it grows new shell and a septa divides the new compartment from the old. These compartments are important in helping the animal maintain buoyancy, balance, and position in the water.

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