A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 125 mm (4.9 inches) tall and the ammonite measures 102 mm, which is very large for this species, and sits in the original limestone matrix in which it was found that has been shaped for display. The ammonite is very well preserved and has been prepared out of the rock to reveal the shell, which displays stunning iridescence, showing many different colours that change as the angle of light changes, with red and orange colours dominating. It is an unusual example as the outer whorl has been naturally eroded due to exposure to the sea but the centre is in perfect condition. It has a cut-flat base and custom plaster wedge on the back to allow it to stand freely for display purposes.
These fossils are highly sought after and very hard to find. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones. The fossil weighs 420 grams.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.