From the Carboniferous,middle Pennsylvanian,Francis creek shale.
Collected from the Braidwood, Illinois,USA.
A Polychaete Worm,Colloquially known as a fish worm,made up of lots of body segments,similar to a millipede!
The specimen is preserved as a white impression, as are most of the Mazon creek Fauna,and would perhaps benefit from a further tap to reveal the rest of it, as it seems to be present, and to continue on underneath the matrix.
The Mazon creek Laggerstatte is really very special,and has brought us some really weird fossils,and this is no exception!
The nodule measures 74mm x 56mm.