A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 175 mm (6.9 inches) across and the ammonite measures 97 mm (3.82 inches), which is very large for this species. The ammonite sits in the original limestone matrix in which it was found that has been shaped and has a cut-flat base 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 causes the colours to change as the viewing angle changes. Deep red, orange and golden tones dominate the shell colour. It weighs 415 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.