From the album: Bryozoan of Minnesota Ordovician
"Batostoma minnesotense" Decorah shale Twin Cities Ordovician. I couldn't tell any difference under digital microscope or by eye examination so any similar species are lumped by me under it. Very abundant in Decorah Shale. Only difference between this and Batostoma fertile is by compare of side by side specimens. Batostoma fertile have larger zoarium that is noticeable with the naked eye.