Heteromorphe-Spiroceras sp. Meek 1876
Middle Jurassic (Bajocian)
Deux-Sèvres, France.

60mm heteromorph on 100mm matrix

Spiroceras sp. (Meek, 1876) is a rare and eye-catching heteromorph ammonite from the Cretaceous period, famous for its tight, helical coil resembling a corkscrew. Unlike the typical flat spiral of most ammonites, Spiroceras took an unusual evolutionary path, possibly affecting how it floated or maneuvered in the water. Its distinct shape and fine ribbing make it a standout among fossil cephalopods—a true testament to the bizarre and beautiful variety of life in the ancient seas.