This Specimen has been sold.
4.7" Polished Ammonite (Promicroceras) Slab - "Marston Magna Marble"
This is a polished piece of rock containing many small ammonite fossils, 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. The base of the rock is flat so the piece stands up nicely 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. 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.