Two Iridescent Ammonites (Psiloceras) - England

This is a pair of brilliantly iridescent ammonites (Psiloceras planorbis) fossil from England. It has a naturally iridescent shell showing nice blues, greens and deep red colors. Like most fossils from the Blue Lias Formation, these ammonites have been compressed and flattened by the same geological processes of heating and pressure which gives them their iridescent shell.

Both ammonites are quite large for the species at 2.1" across and have a lot of flash. A beautiful piece.

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.

What an ammonite would have looked like while alive.

More about ammonites