Corals Corals lived in the warm shallow sea which covered southeastern Minnesota during the Ordovician and Devonian ages. Corals can be found in outcrops of the Prarie du Chien, Plattville, Decorah, and Galena. Trilobites The thee segmented trilobite roamed the floors of the Paleozoic seas hunting and scavenging. Trilobites can be found in the Decorah formation, notably at Wang's corners near Dennison. Graptolites Graptolites formed colonies of thin branches from the earlier part of the Paleozoic.
Fossils look like pencil marks on the rock.
Graptolites can fe found in the Platteville and Galena. Cephalopods Cephalopods are the largest fossils found in the area with some as large as 14 feet long. Gastropods can be found in the Prarie Du Chien, Platteville, Decorah, and Galena. Unlike brachiopods each of there two shells is a mirror image of the other. Pelecypods are found in the Ordovician limestones of the area.