The Roubidoux Formation is a geologic formation in Missouri’s Ozarks that preserves fossils from the Ordovician period, making it an important part of the region’s deep geological history. Fossils reported from it include monoplacophorans such as Kirengella oregonensis and Wildernessia inexpectans, as well as the gastropod Lecanospira perplana. Its importance rests on this preserved fossil record, which identifies the formation as one of Missouri’s fossil-bearing stratigraphic units.