Placenticeras meeki with partial concretion, umbilicus and standard base

This 73.5 Million Year old Cephalopod was a fast-moving nektonic carnivore that hunted fish and other mollusks in the ancient Western Interior Seaway of North America. Their shells could reach 1 meter in size, they were involute (grew over the top of their old shell), and their inner phragmocone sections display both its sutures patterns and original shell iridescence called Ammolite.

 The Calcite lining the internal chambers, entered the Ammonite during the last Ice Age, 40,000 years ago. Erosion allowed meteoric water to dissolve calcium carbonate from the shale and redeposit them inside the fossils within the concretions. The Calcite also Fluoresces bright yellow under UV light.