Sterling Jasper? stone or wood artisan 2024 pendant

This is a unique stone pendant, not sure if this is a jasper or petrified wood or something else. It looks like a turtle's back. It is set in a sterling bezel setting. Marked '925' at the bail. The height is 2.1 inches and width is 1.2 inches and 2024 weighs 17.8 grams.