Origin: Pierre Shale Formation, Elk Creek, South Dakota
These rare ammonite fossils date back 73 million years and are preserved in protective concretions. Once floating in ancient warm seas, their coiled shells contained gas chambers for buoyancy. Distinct layers of the surrounding concretions correlate with meteorite impacts that caused massive tsunamis, forming these unique fossilized mud balls. Known for their colorful, iridescent preservation, these ammonites are highly sought after for their beauty and historical significance.
