Ammonites are invertebrates and extinct members of the subclass Ammonoidea, class Cephalopoda. Ammonites began appearing during the Middle Devonian period about 400 million years ago that were mollusks, with shells that were tightly coiled on a single plane and were known as Homomorphs. As they matured and grew larger, chambers were added at the opening. The shells of ammonites had hollow chambers separated by walls called septa. The outer ornamentation increased over time with outward ribs, ridges and spines. This huge ammonite we are offering is from the Jurassic Period 145-201 million years ago. There has been no restoration, or added material to this specimen. The fossil comes with a Heavy-Duty hand-forged steel stand that we fabricate.