Dalmanella is a very common brachiopod in the Ordovician. In the Verulam formation their shells sometimes cover an entire bedding plane.
This piece of matrix has many Dalmanella along with Sowerbyella and other brachiopods.
A smaller piece from the same layer shows more detail. I'll bet if I had an air compressor and some micro abrasive there would be a lot more to look at on these two pieces.
Here is a loose, solitary shell: Pedicle valve
It's possible to find this same genus in the upper Ordovician aged rocks around Cincinnati. The fossils shown above came from a quarry near Brechin, Ontario and are middle Ordovician (Katian/Mohawkian stage) in age.