First trip of the year to Decorah Shale Formation in Ordovician Minnesota. This was one of the few fossils I found - I assumed it was a regular Large Gumdrop Bryozoan, Prasopora conoidea. Then when I got to cleaning the clay and soft shale off it looks so different. No noticeable pores and sharp angles. Here's two Large Prasopora conoidea - one smooth form and one rough and layered form on the left side for comparation. There is also a little Hormotoma fragilis gastropod on top. It doesn't even look like a trace fossil, as trace fossils are usually harder than usual shale or gathering of coarse sediments.