Within the Widder formation you often find a Rhyconellid brachiopod that is flattened or otherwise distorted. I referred to them as Leiorhynchus until I found this picture hosted on the Friends of the UMMP Website which calls it Eumetabolotoechia cf. multicostum. The specimen below is rare in that it's inflated (rounded and not flattened) and complete.
I like the pearlescent shell remnants that are present. It's not actual shell but more likely recrystallized by the pressure of being buried and fossilized.