A major mystery of paleontology

Object of the Month: 01/2015

What is it?:

Tullimonstrum gregarium


Pennsylvanian Age

Age: About 300 million years
Where was it collected:

Grundy County, Illinois


Range from 36 to 340 millimeters

What is it made of?:

Ironstone concretion

Accession #: SMM P71.17.1

A model of Tullimonstrum (left) and a concretion impression give us views of what this ancient sea creature looked like.

What can this be? It’s a question that still puzzles paleontologists. Tullimonstrum was a worm-like or snail-like creature. We do know that this sea-living creature dates back some 300 million years. The fossil impression you see here came from the coal shale of Illinois.

The accompanying full-body model shows some strange features of Tullimonstrum. Its eyes are located on the ends of stalks on either side of its body. It had a long proboscis, like an elephant’s trunk, with small teeth at the end to capture prey. The proboscis delivers the prey to the mouth located in the middle under belly of the creature. It swam about powered by its squid-like tail.

The brown fossilized impression is preserved in an ironstone concretion of delta sediments that formed around the animal shortly after it died and settled to the bottom of the sea. The impression shows only the lower proboscis and upper torso of the creature. It's estimated length is 170 millimeters. This specimen shows Tullimonstrum's underside with the bar organ containing optic nerves and the left stalk of the eye structure. The tail is missing.

The drawing on the left depicts how the creatures likely lived in open ocean water near shore and aquatic plants. Tullimonstrum was preyed on by bony fishes and sharks.

Feeling creative? Try writing your own label to explain Tullimonstrum to other museum visitors in the box below.

Your Comments, Thoughts, Questions, Ideas

muirann's picture
muirann says:

it looks like a cobra and a fish mixed together

posted on Fri, 01/02/2015 - 12:48pm
MAX's picture
MAX says:


posted on Fri, 01/02/2015 - 8:18pm
kas's picture
kas says:

it is an aquatic animal that lived 300 million years ago

posted on Sat, 01/03/2015 - 4:42pm
JACKSON     's picture


posted on Sat, 01/31/2015 - 3:43pm
Abi's picture
Abi says:

The nose is like one of an aardvark and the eyestalks like a snail, otherwise it looks like a squid with one tentacle.

posted on Sun, 01/04/2015 - 10:57am
finn's picture
finn says:

It looks weird and the way that its eyes are on stalks. I think it ate seaweed and small fish. I like the feature of its squid like tail. I would not like to eat it because it would be slimy and crunchy. I wonder if it has a shell like you know how some fish have a potective layer. It is very small and I think a lot of other creatures ate it. It may have been fast.

posted on Sun, 01/04/2015 - 1:19pm
sthe's picture
sthe says:

it looks like a fish a weird fish

posted on Tue, 01/06/2015 - 2:58pm
bigfoot's picture
bigfoot says:


posted on Sat, 01/10/2015 - 5:35pm
PEYTON S's picture
PEYTON S says:


posted on Sat, 01/10/2015 - 3:04pm


posted on Sat, 01/10/2015 - 3:49pm
Jacob's picture
Jacob says:

It looks like stingray

posted on Sun, 01/11/2015 - 10:32am

It looks like a cobra and a lizard who livesin the grass

posted on Sun, 01/11/2015 - 2:35pm
Clara Johnson's picture
Clara Johnson says:

It looks like it came from a childs worst fear with the smallness of it but the eyes are sticking out and look scary, plus probally having lots of preadators, it could swim fast and come and get you! Duhn, Duhn, Duhn!

posted on Sun, 01/11/2015 - 2:41pm
Robin 's picture
Robin says:

This interesting aquatic creature may possibly be related to both Angler Fish and eels which would exlain some of it's characteristics/physical features and may perhaps have acted much the same way. For example, it's proboscis may have served much like the Angler Fish's lure appendage enchanting prey to come close enough for it to "pounce" and enjoy. Also it's physical appearance being somewhat similar to an eel may have helped it glide swiftly through strong currents.

posted on Thu, 01/15/2015 - 1:42pm
WhitWolf's picture
WhitWolf says:

Its not a leech

posted on Thu, 01/15/2015 - 1:51pm
kat's picture
kat says:

A Swimming Snail?

300 million years ago, this mysterious creature roamed the seas. Its nose is like an elephant's trunk, and its tail is like a squid--it's a Tullimonstrum!

posted on Fri, 01/16/2015 - 11:09am
brady 24's picture
brady 24 says:

they are sometimes big

posted on Fri, 01/16/2015 - 1:59pm
ACD's picture
ACD says:

I wonder who found the specimen. It's truly amazing. The squid-like tail and the odd eyes make it kinda look like an alien. But don't get me wrong, this could be the discovery of the century.

posted on Fri, 01/16/2015 - 6:18pm
Adrien's picture
Adrien says:

Looks like snake and a dinosaur together

posted on Sat, 01/17/2015 - 1:49pm
Mia's picture
Mia says:

It looks like a worm mixed with a lizard! IT IS WEIRD

posted on Sat, 01/17/2015 - 4:58pm
ellory's picture
ellory says:

its mouth was on the bottom!

posted on Sun, 01/18/2015 - 10:29am
BUBU's picture
BUBU says:


posted on Mon, 01/19/2015 - 2:15pm
Andi's picture
Andi says:

I think it could be the begining of a salamander or a newt.

posted on Mon, 01/19/2015 - 2:18pm
Caitlyn Hirsch(Brynn Hirsch's sister)'s picture
Caitlyn Hirsch(Brynn Hirsch's sister) says:

It kind of looks like a swordfish with flippers in the back.

posted on Mon, 01/19/2015 - 3:15pm
Thalie's picture
Thalie says:

It's feet look like monster eye-balls.

posted on Mon, 01/19/2015 - 4:14pm
Jade Jones's picture
Jade Jones says:

In my opinion this looks like a fsh mixed with a gecko.

posted on Wed, 01/21/2015 - 2:13pm
st paul winter carnival visiting ambassados's picture
st paul winter carnival visiting ambassados says:

leaf creature??????

posted on Fri, 01/23/2015 - 11:28am
elena's picture
elena says:

i thingk it is a eel

posted on Fri, 01/23/2015 - 11:55am
finley anfinson's picture
finley anfinson says:

i think they look like (1)a rock (2) a cobra mixed with a eel.

posted on Sat, 01/24/2015 - 2:40pm
katelyn liu's picture
katelyn liu says:

It looks like a newt and an eel combined.

posted on Sun, 01/25/2015 - 3:17pm
Kimberly's picture
Kimberly says:

I think it fed on cril like whales and ate lots like a bat
the eyes on the sige are/were for the nimal to use like a hamerhead shark.

posted on Sun, 01/25/2015 - 3:44pm
Marquise Smith's picture
Marquise Smith says:

Scientist discover this fascinating 300 million year old aquatic creature, in Grundy County Illinois. Identical to a blood sucking leech, this snail like creature preyed on bony fishehs and sharks and is made out of ironstone concretion.

posted on Tue, 01/27/2015 - 5:16pm
Andrew 's picture
Andrew says:

The tullimonstrum gregarium it is a interesting animal. also a peculiar anmal

posted on Sat, 01/31/2015 - 5:23pm

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