Tullimonstrum, better known as the Tully monster, is the official state fossil of Illinois, living around 300 million years ago in the Carboniferous period. It is famous for its strange body plan: a soft, torpedo-shaped body ending in a pair of stalked eyes and a long proboscis tipped with a tooth-lined jaw, the exact identity of which has puzzled paleontologists for decades. It likely scoured the muddy seafloor of the Mazon Creek lagoons, sifting through sediment with its flexible snout in search of small prey. Because its body was entirely soft, Tully monsters only survive as rare imprints in the fossil record, making them one of the most mysterious animals of the Paleozoic.\n