Looking very much like an Athyris sp. brachiopod, this fossil is Cleiothyridina hirsuta. It is a rounded to subovate shell with both the pedicle and brachial valve equally convex. The surface of each valve has concentric growth lines but no obvious costae or sulcus.
I used the reference "Brachiopoda of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming.", MacKenzie Gordon, Jr., 1975 pg. 56, plate 7, fig 31, 38-40, 42-45, 58, 59 to identify this brachiopod. This
specimen came from the Chainman formation at Conger Springs (west of
Delta), Utah and is Carboniferous (Mississippian epoch, Visean stage of
the ICS or
Mississippian period, Chesterian stage in the US) in age.