An unusual example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 102 mm (4 inches) tall and the ammonite measures 72 mm (2.8 inches). The ammonite sits in the original limestone matrix in which it was found that has been shaped and has a cut-flat base to allow it to be displayed freely standing. The ammonite is very well preserved and has been prepared out of the rock to reveal the shell, which displays some beautiful subtle iridescence that causes the colours to change as the viewing angle changes. There are red and orange hues with a general pearlescent sheen. This one is unusual as it also has a bivalve shell that encrusted the ammonite shell, probably after the animal died and the shell lay on the seafloor. This provides a real snapshot of natural history. The fossil weighs 250 grams.
These fossils are highly sought after and hard to find. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones. These fossils make great unusual gifts and each one is totally unique.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.