Devonian Fossil Cluster

I found this neat fossil at an art/fossil store in Minocqua, WI. They had a small inventory of fossils, mostly whole Trilobites, Ammonites, and some crystals. They had this fossil labeled as a Devonian fossil cluster, 350 - 416 million years old. I immediately assumed it was of marine origins, but now that I have it home, it occurs to me that it could be terrestrial. Any fossil afficianados out there want to hazard a guess at what these little...things are?

Click on the photos to see the huge detail version.