This fossil is the impression of an ammonite, not an actual ammonite. It lent itself to becoming the lid of a box. We sometimes gently oxidise the silver by leaving it in a sealed plastic bag with a hard-boiled egg. You never know what will happen but in this case it was a great success – tiny dots appeared on the inside along with various other interesting colours and markings.

Fossilised impression of an ammonite; silver; 18 carat gold

Approximately 4 cm across