Ammonites & Ammolites

Ammonites are a group of extinct marine mollusks that lived from the Devonian to the late Cretaceous. The nautilus is their closest living relative. Ammonites fossils have been observed since the medieval times and have been linked to Christian and Egyptian myths. Even today, they are commonly used as charms, ornaments or even as feng shui "crystals". The most expensive and sought-after ammonites come from the Bearpaw Formation; those with opal-like qualities are considered biogenic gemstones and known commercially as ammolites.