Here are another couple of Ostracod fossils from the Arkona Shale. They are Quasillites and I think they are Q. concentricus. They stand out because of the fingerprint like pattern on the surface.
I found the above specimens from a piece of the Arkona Shale that I soaked overnight in some water and then screened. The Arkona Shale is middle Devonian in age (Givetian stage).