The coiled shell served as protection and support. A highly complex suture occurs where internal partitioning walls come in contact with the outer shell wall.
Ammonites are relatives of squid, octopus and the chambered nautilus.
They went extinct 65 million years ago with the dinosaurs. While they lived they evolved quickly so that some species only lived for a relatively brief period of geologic time. Hence they are excellent fossils for dating of rocks. Several ammonites were found with and surrounding the dinosaur bones. Dr. Peter Rodda have allowed us to more accurately date these rare dinosaur era remains.