5.8" Polished Section Of Promicroceras Ammonites In Cross-Section

Polished Section Of Promicroceras Ammonites In Cross-Section #129296

This is a polished free standing piece of rock containing many ammonite fossils in cross-section. This material is often referred to as "Marston Magna Marble".

The ammonites are of the species Promicroceras marstonense and are Lower Jurassic (~200 million years old) in age. This rock is quarried from near Marston Magna, Somerset, England and by slicing and polishing it the beautiful inner chamber detail of the ammonites can be seen.

One face of this specimen has been polished, while the opposite side with a few ammonites poking out. The base of the rock has been cut flat for presentation purposes.

Ammonites were predatory cephalopod mollusks that resembled squids with spiral shells. They are more closely related to living octopuses, though their shells resemble that of nautilus species. True ammonites appeared in the fossil record about 240 million years ago during the Triassic Period. The last lineages disappeared 65 million years ago at the end of the Cretaceous.

What an ammonite would have looked like while alive.