Carolowilhelmina geognostica is an extinct arthrodire placoderm fish that lived in the Late Eifelian epoch of Aragon, Spain. In life, C. geognostica was a long-snouted pelagic fish, superficially similar to the Australian Rolfosteus and the European Oxyosteus. It is currently known only from an incomplete cranium that is about 43 cm (17 in) long. The fossil material is housed in the Natural Sciences museum of the University of Zaragoza, Spain.