Ammonoids are extinct aquatic creatures that lived between 400 to 65 million years ago. They were cephalopods and had a coiled-shell which served as a protective covering and a buoyancy device. There are various synonyms that are associated with the word "ammonoids" such as Ammonitida, Ammonitina, and Ammonoidea. These synonyms are often used interchangeably by paleontologists and geologists when referring to the fossilized remains of these creatures. Ammonoids were once abundant and diverse and were used as biostratigraphic markers to study the Earth's geologic history. Studying Ammonoids provides valuable insights into the evolution of invertebrate life and helps researchers understand the biodiversity of the ancient world.