A thin section depicting a cross section of a Psaronius stem (bottom left) and inner root mantle (top right) from a Pennsylvanian coal ball (~300 million years ago) taken using a Zeiss Axio Zoom V16. Psaronius is an extinct Marattiaceae tree fern which grew 30 - 50 feet and was widespread during much of the late Pennsylvanian period in Euramerica. This image is a part of an effort to digitize the University of Illinois Phillips Coal Ball Collection.