What is Tullimonstrum?
{{italictitle}} {{Automatic taxobox | fossil_range = {{fossil range|Middle Pennsylvanian}} | image = Tullimonstrum gregarium 343.JPG | image_alt = | image_caption = The ''Tully Monster''<br />''Tullimonstrum gregarium'' fossil<br />(part and counterpart) | taxon = Tullimonstrum | authority = Richardson, 1966 | type_species = ''Tullimonstrum gregarium'' | type_species_authority = Richardson, 1966 }} '''''Tullimonstrum''''', colloquially known as the '''Tully Monster''', is an extinct [[bilateria]]n [[animal]] that lived in shallow tropical coastal waters of muddy [[estuary|estuaries]] during the [[Pennsylvanian]] geological period, about 300 million years ago. A single species, T. gregarium, is known. Its classification has been the subject of controversy, and interpretations of the fossil likened it to [[mollusc]]s, [[arthropod]]s, [[conodont]]s, [[worm]]s, and [[vertebrate]]s. It is unknown whether ''Tullimonstrum'' was a [[vertebrate]] or an [[invertebrate]]. [[Category:Animals]] [[Category:Extinct species]] [[Category:Fossils]] {{biology-stub}}