A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 195 mm (7.7 inches) tall and contains a single complete ammonite that measures 80 mm (3.15 inches), which is large for this species. It weighs 1145 grams and the matrix has a cut-flat base for display.
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 iridescence with a wide range of colours, including green, gold, and copper with flashes of purple that appear as the viewing angle changes.
Several cracks in the matrix and shell have been stabilised and there is an unusual bivalve shellfish preserved on top of the centre of the ammonite. The shell grew in the same shape as the ammonite. There is also part of another ammonite next to the main one, which shows a deep green colour.
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.