Holocystites Cystoid Fossil

 

Earlier this month, I was able to attend a field trip to Napoleon, Indiana USA. While there, I found this fossil which appears to be a Holocystites cystoid. It dates to the Silurian Period  (Telychian to Sheinwoodian stage) in age. The locality is world famous for this type of fossil. It has not been prepped yet which would reveal is detailed surface texture and plates.

According to Dr. James Thomka, professor at SUNY Plattsburgh, it is "from the mudstone lithofacies of the Massie Formation (long known as the "upper Osgood shale"), which is renowned for its 'cystoid' fauna."