Wikipedia
Euhoplites is an extinct ammonoid cephalopod from the Lower Cretaceous, characterized by strongly ribbed, more or less evolute, compressed to inflated shells with flat or concave rims, typically with a deep narrow groove running down the middle. In some, ribs seem to zigzag between umbilical tubercles and parallel ventrolateral clavi. In others the ribs are flexious and curve forward from the umbilical shoulder and lap onto either side of the venter.
Fossils of this animal are commonly found in Lower Cretaceous, Albian age strata with some coming from the Upper Cretaceous Cenomanian.
Its shell was covered with lumps and bumps. The function of these adornments are unknown, although they may have been a source of hydrodynamic drag, preventing Euhoplites from swimming at high speeds. Studying them, therefore, may give some insight into the lifestyle of this ancient marine predator. Euhoplites was a small Ammonite with shells of diameters of at most a few inches in diameter, depending on the age, species and possibly gender of the individual.