the Tully monstrum

The Tully Monster (Tullimonstrum gregarium), yet apparently the only species of Genus found in Illinois (USA), was a soft-bodied invertebrate that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian (Carboniferous period), about 300 million years ago.
Tullimonstrum gregarium named after its discoverer, Francis Tully .
Tullimonstrum probably reached the length of 35 inches, but smaller individuals were of about 8 cm .
The monster Tully had a pair of wings not different from those of cuttlefish towards the end of the body, the vertical blades (although the conservation status of the fossils of its soft body makes it difficult to determine) and a long proboscis with eight small teeth sharp through which you can actively probed the muddy bottom in search of small creatures and debris edible. The proboscis of Tullimonstrum is rarely preserved in its entirety, and is complete in about 3% of the samples. However, a part of the organ is preserved in about 50 % of cases.
The absence of hard parts of the fossil implies that the animal did not possess bodies composed of bones, chitin or calcium carbonate. Internal structures are evident in repeated series, while the head is poorly differentiated. A structure in the shape of the transverse bar presents dorsally or ventrally, and ends in two round bodies which appear associated with dark material similar to the pigmentation often found in the eyes. Their shape is indicative of a structure type camera.
There is insufficient evidence to align Tullimonstrum at the top of a group of primitive phyla.Because it lack of well-known characters of modern phyla, it has been hypothesized that it is the representative of an ancestral group of one of the many phyla of worms that are poorly represented today. We have also noted similarities with fossils of the Cambrian organisms as Opabinia. Tullimonstrum was probably a natant carnivore that lived in open marine waters.
The Tullimonstrum is part of the ecological community represented by the unusually rich group of soft-bodied organisms found in the assembly called Mazon Creek fossils from their site in Grundy County, Illinois.
The formation of Mazon Creek fossils is unusual. When the creatures died, were quickly buried in muddy sediments. The bacteria that decomposed plants and animals produced carbon dioxide in the sediments around the remains. The carbon dioxide is combined with iron minerals, further slowing down the degradation of the material and leaving a carbon film on them.
The combination of rapid burial and the rapid formation of siderite caused an excellent preservation of many animals and plants that ended up in the mud. The result is that the of Mazon Creek fossils are one of the leading Lagerstätten the world (associations of fossils concentrates).
The amateur collector Francis Tully found the first of these fossils in 1958. He gave the strange creature at the Field Museum of Natural History, but paleontologists are still perplexed about the phylum whichTullimonstrum belongs.
Tullimonstrum gregarium was officially designated the state fossil of Illinois in 1989.