A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The piece of thin limestone matrix measures 82 mm (3.25 inches) tall and contains a single partial ammonite that measures 71 mm (2.8 inches).
The ammonite is very well preserved and has been prepared out of the rock to reveal the shell, which displays some stunning iridescent colours that change depending on the angle that the fossil is viewed at. There is a beautiful mix of green, gold, and orange colours in the shell - making some of the strongest colours possible in these fossils. It weighs 90 grams.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection. These fossils are preserved in the same way as the more famous Canadian "ammolite", which is turned into valuable gemstones due to the stunning iridescence.