Any guesses what this brachiopod might be called?
UPDATE: It appears this brachiopod cannot be from the Ordovician Period so either I mixed it up with another fossil batch or someone dropped it there. I visited the area again and could not find anything close to what this one looks like. It does look like a Mississippian Period Cleiothyridina sublamello from the Glen Dean Formation of Indiana. See the fossilicious.com web entry for a picture. The size they describe would make it much larger than the one pictured here.
Commissura or margin where shell halves open and close (anterior).
It was the only one I found in a plane of maybe 20 or so other brachipods. The other brachiopods found were these Dalmanella sp. (a.k.a. Onniella)
The other type of brachiopod found were these Sowerbyella sp.