A very common brachiopod from the lower Devonian is Meristella. It is likely the most common brachiopod that I found in the Kalkberg formation of NY when collecting a couple of months ago. The specimens below are Meristella arcuarta and are among the few whole, intact specimens that I found. More often I found isolated, disarticulated valves or they were somewhat crushed even more than the first specimen below. M. arcuata is a round to oval shaped shell that is longer than wide with both valves being convex. The shell surface is smooth except for occasionally strong concentric growth lines. The pedicle valve curves back to a beak with a round foramen is found which is where the pedicle muscle extended in life. The pedicle vale features a sulcus that is only really expressed at the margin of the shells.
Specimen #1 - Pedicle valve
Specimen #2 - This is a bit better inflated specimen but there is still some matrix adhering to the surface of the brachial valve.
Something that is pretty cool are the epibionts that encrust the surface of the shell. It looks like some colonies of the bryozoan Lichenalia maculosa.
The Kalkberg formation is lower Devonian in age (Lockhovian to Pragian
stage). I collected this specimen from a roadcut near Shoharie, NY.
I have posted previously about many different species of Meristella like M. atoka from the Haragan Fm. of Oklahoma, M. arcuata from the Onondaga Fm. of New York, and M. obtusa from the Wenlock Fm. of England.