Placenticeras costatum with botryoidal Barite

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 foot in size, they were involute (grew over the top of their old shell), and their inner phragmocone sections display both its suture patterns and original shell iridescence called Ammolite.