A stunning example of an iridescent ammonite fossil of the species Caloceras johnstoni from North Somerset, UK.
The matrix measures 78 mm (3.1 inches) across and contains a single partial ammonite that measures 57 mm (2.3 inches). It has an unusual geological fault running through the shell.
The ammonite is well preserved as a half and has been prepared out of the rock to reveal the shell, which displays some stunningly bright iridescence that changes as the viewing angle changes, with green, orange, and red colours present.
The shell sits in the original thin piece of limestone shale matrix in which it was found that has been shaped and has a cut-flat base that allows it to stand by itself for display. The whole piece weighs 95 grams.
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. 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.