Inversoceras

Inversoceras is a genus of cephalopods in the order Oncocerida and the family Trimeroceratidae. These mollusks were fast-moving nektobenthic carnivores. They lived in the Silurian period, from the Lower Wenlock age (428.2 ± 1.5 to 422.9 ± 2.8 mya) to the Ludlow age (422.9 ± 1.5 to 418.7 ± 2.8 mya).
Distribution.
Silurian of Sweden, United States (Wisconsin).