Huge and Exceptional Polished Ammonite Fossil Disc Polished ammonite plate, formed of individual ammonites 30.6cm in diameter Weighs 1.824 kg In excellent condition Pictures form part of description and condition report Stand not included Will be shipped with insurance Ammonites are a form of ammonoid which are distinguished by their complex suture lines. They evolved very rapidly to produce numerous species and genera, but it was during the Late Cretaceous period that the ammonites and other marine groups, like belemnites, and terrestrial groups, like dinosaurs became extinct. The name ammonite, was inspired by the spiral shape of their fossilized shells, resembling tightly coiled rams’ horns. Many ammonoids probably lived in the open water rather than at the sea bottom, this is due to the fact that their fossils are often found in rocks that were laid down under conditions where no bottom-dwelling life is found. They are typically evolute with the inner whorls exposed, but some are commonly stout and more involute and strongly ribbed with pronounced tubercles.