A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 80 mm (3.2 inches) across and contains a single partial ammonite. The shell sits inside the original limestone in which it was found that split perfectly to reveal the positive and negative portions of the fossil. The pieces go back together so can be kept as the original rock with a surprise inside! The shell displays some beautiful rainbow iridescence with deep red, orange, and green colours that appear as the viewing angle changes. This one really has spectacular colours.
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 50 grams.
Around 200 million years old (Hettangian, Early Jurassic), this fossil would make a wonderful addition to any collection.