Male and female?
This specimen has been broken and restored, and its missing centre has been replaced with a small specimen of the same type of ammonite. But it is still quite beautiful and unusually large. This was probably a female ammonite, bigger than the males of the species as extra room was needed to carry eggs. Below is a possible male Asteroceras. It has an unusually short body chamber which is thought to be a possible indication of sexual dimorphism; a difference between males and females of the same species.
Find out more about ammonites on the molluscs pages.