Asteroceras obtusym

Asteroceras obtusym, the Obtuse Star Ammonite, is an extinct species of cephalopod belonging to the Ammonite subclass and to the family Arietitidae. These fast-moving nektonic carnivores lived during the lower Jurassic period, upper Sinemurian, around 189-196 million years ago.
Asteroceras obtusym has a shell reaching a diameter of about 8–20 centimetres (3.1–7.9 in).