The Tully Monster is one of the greatest mysteries in paleontology. Discovered in Illinois, this 300-million-year-old fossil has baffled scientists for decades. With its strange tubular body, stalked ...
the Tully monster (Tullimonstrum gregarium) is an enigmatic creature that lived about 300 million years ago. Unique to the Mazon Creek Formation in Illinois, it became its state fossil in 1989.