Dissimilites sp.
Early Cretaceous (Hauterivian)
Alpes-de-Haute-Provence
France

A fossil specimen of Dissimilites sp., a rare heteromorph ammonite from the Cretaceous seas. Unlike typical tightly coiled ammonites, Dissimilites developed an irregular, partially uncoiled shell form, making it one of the more unusual cephalopods of the Mesozoic marine world.
47mm heteromorph ammonite on 111mm matrix