Uncommon Asteroceras Ammonite Fossil - England

This is a uncommon Asteroceras obtusum ammonite fossil from the Lyme Regis region of England which has been agatized. It's almost translucent and has been nicely prepared so that it displays nicely in a slab of limestone. The base of the limestone has been cut flat so it displays nicely without the need for a display stand.

About Ammonites

Ammonites were ancient marine cephalopods, similar to today's squids and octopuses, but with a defining feature: their distinctive, tightly coiled spiral shells. These shells, resembling those of modern nautiluses, served as both a protective home and a buoyancy aid, allowing ammonites to navigate the prehistoric seas with ease. First emerging around 240 million years ago in the Triassic Period, ammonites thrived for over 175 million years, adapting through numerous forms and sizes. As predatory creatures, they likely fed on smaller marine organisms, using their tentacles to capture prey. However, their long reign came to an end 65 million years ago at the close of the Cretaceous, coinciding with the mass extinction event that also eliminated the dinosaurs.

What an ammonite would have looked like while alive.