Several fossils have been discovered in the Stump Cross system. The initial discoverers of the caves found four near-complete reindeer fossils and a smaller skeleton believed to be that of an unborn reindeer. These have since been privately restored. Christoper Long’s 1922 exploration also revealed more prehistoric reindeer bones and those of wolverines. The wolverine bones are now on display at the site’s visitor centre. Bison remains have also been found.