Name:   Fossil Seed Fern Plate Age:  Pennsylvanian Formation:  Llewellyn Formation Location:  Near St. Clair, Pennsylvania Size:  Plate is almost 10 inches across This is a nice, displayable fossil seed fern plate from the famous location at St. Clair, Pennsylvania. There are many fine fronds on the plate. The seed ferns are preserved as a thin film of white pyrophyllite on black shale. There are a few different sizes of ferns preserved. And there are even nice ferns on the back side of the plate. This is a very distinct slab of Coal-Age plants from this classic site.