Tripteroceroides
Nautiloid
Lower Mississippian (Meramecian)
St. Louis Limestone
Waterloo, Illinois, USA

90mm block of silicified limestone with multiple nautiloids.

Cephalopod. Jumble. Association. Multiple.

Tripteroceroides is a genus of straight-shelled nautiloid known from the Carboniferous of Kazakhstan and the American Midwest. They have been preserved as silica (glass) and were etched out of a solid block of limestone with acid. Very unusual.

There’s a lot going on in this eerie tableau – nautiloids preserved with a ghostly look. You could add this to your Halloween display.