A highly pyritised ammonite fossil of the species Promicroceras pyritosum from the world-famous Jurassic Coast beach of Charmouth, Dorset UK.
The fossil measures 17 mm (0.7 inches) across. The ammonite is very well preserved on both sides. There are multiple unusual serpulid worm casts on the shell that would have encrusted it in life. Two of them run side-by-side along the keel of the shell. The ribs are very finely defined and the pyritic colour and shine is beautiful. A great example of the species and incredible in the flesh.
These pyrite ammonites have long been used to make beautiful natural jewellery.
Around 196 million years old, this fossil would make a wonderful addition to any collection.