A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 120 mm (4.72 inches) tall and contains a near-complete ammonite that measures 81 mm (3.2 inches) across, which is large for this species. The shell sits in the original limestone matrix in which it was found that has been shaped and has a cut-flat base and rock-coloured plaster wedge on the back 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 iridescence that changes as the viewing angle changes, with most of the colours of the rainbow appearing at certain angles. It's rare to get this range of colours in these ammonites.
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 150 grams. 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.