This Specimen has been sold.
.9" Agatized Fossil Ammonite (Promicroceras) - Lyme Regis
This is a very beautifully agatized, .9" Promicroceras planicosta ammonite fossil, collected from Lyme Regis, England. It's almost translucent and has been nicely prepared so that it displays very well on the limestone slab. This specimen has the impression of a second ammonite and what appears to be a third ammonite still encased in the limestone.
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. True ammonites appeared in the fossil record about 240 million years ago. The last lineages disappeared 65 million years ago at the end of the Cretaceous.