6.7" Fossil Ammonite (Euhoploceras) - Somerset, England
This is a 6.7" Euhoploceras (Sonninia) acanthoides ammonite fossil from Yeovil, Somerset, England. It is Middle Jurassic in age, or approximately 160 million years old. The base of the rock has been cut flat so that it stands up without the need for a display stand.
Ammonites were predatory mollusks that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. Ammonites appeared in the fossil record about 240 million years. The last lineages disappeared 65 million years ago at the end of the Cretaceous.