Miocene
Lincoln Creek Formation
Grays Harbor County, WA, USA
Extremely rare near complete 25mm nautiloid preserved in translucent chalcedony
Nautiloid,  Cephalopod.

Aturia is a nautiloid genus known from the Paleocene to Miocene of various sites worldwide but an elusive find at all its known localities.

Nautiloids appeared late in the Cambrian Period but ascended to the level of apex predator early in the Ordovician Period.  They persevered against serious competition from various jawed fish groups during the Devonian.  They endured minor and major extinction events all the way into the Early Cenozoic Era, a time when they rediversified before going into decline by the Late Miocene.  Today, only a few species survive in the deeper parts of the Indo-Pacific region.

This one has a nice degree of translucence rarely seen in a fossil.