A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 86 mm (3.4 inches) across and contains a large near-complete ammonite. It weighs 72 grams and the matrix has been sculpted around the ammonite.
The shell sits in the original limestone matrix in which it was found. The ammonite is very well preserved and has been prepared out of the rock to reveal the shell, which displays some beautiful multicoloured iridescence with flashes of orange, green, and gold that appear as the viewing angle changes.
These fossils are highly sought after and very hard to find, especially complete like this. They are preserved in the same way as the famous Canadian "Ammolite" ammonites that are turned into valuable gemstones.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.