This is a polished palm stone ammonite fossil in a stone bed. This is approximately 2.4 inches long.
History of Ammonites
There were many different types of ammonites dating between the Jurassic and Devonian periods (65 and 419 million years ago). The more complex the ammonite fossils, the more recently they were created in those periods. Ammonites died away at the same time as the dinosaurs.
Ammonites (subclass Ammonoidea) can be distinguished by their septa, the dividing walls that separate the chambers and are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopada. These molluscs are more closely related to living coleoids such as octopuses, squid, and cuttlefish.