Scientists believed that ammonites, like modern cephalopods, had soft body tissue with tentacles attached to their heads for catching prey. Fossil evidence indicates they had sharp, beaklike jaws ...

Ammonites' shells make the animals look most like nautiluses, but they are actually thought to ... although a variety of shapes did evolve over time. Shells could be a loose spiral or tightly curled ...

The process of opalization refers to something turning into an opal — like for example, a big part of this fossil. Opalized ammonite fossils are formed through a unique geological process ...