Meet the Tully Monster: The Prehistoric Bizarre-o That Science Still Can’t Figure Out

If you asked a group of paleontologists to design the most confusing creature imaginable, they probably couldn't top what nature came up with 300 million years ago.

Enter Tullimonstrum gregarium—affectionately known as the Tully Monster.

This strange little marine critter lived during the Pennsylvanian geological period, swimming around the muddy tropical estuaries of what is now Illinois. It didn't have bones, a hard shell, or a traditional face. Instead, it looked like someone smashed together a slug, a squid, an alien, and a pair of long-handled pliers.

Even after decades of study, scientists are still arguing over what on Earth this thing actually was. Here’s the story behind paleontology’s favorite weirdo.

1. Discovered by an Amateur in a Coal Mine

The Tully Monster wasn't discovered by a world-famous professor in a high-tech lab. It was found in 1958 by Francis Tully, an amateur fossil hunter scouring the Mazon Creek coal mining waste piles in Illinois.

When he cracked open a reddish ironstone nodule, he found a impression of a creature unlike anything in the history books. He brought it to the Field Museum of Natural History in Chicago, where experts essentially stared at it, shrugged, and admitted they had no idea what they were looking at. They eventually named it after him!

2. Eyes on a Stick and a Claw on a Hose

Nothing about the Tully Monster's anatomy makes sense at first glance:

• The Eyes: Instead of sitting on its head, its eyes were mounted at the ends of a rigid, horizontal bar sticking out from its torso—like a pair of binoculars on a stick.

• The Snout: It had a long, flexible, trunk-like proboscis extending from its front, tipped with a small, toothy claw or pincer.

• The Body: A soft, shovel-shaped body with fins on the back end for steering.

Imagine an animal using a tiny claw-arm to grab prey while scanning the water with wide-set eye-stalks. It sounds like a monster from a retro sci-fi comic, yet it genuinely swam in our ancient oceans.

3. Is It a Fish? A Worm? A Slug? Nobody Agrees!

For over 60 years, the biggest debate in paleontology has been a simple question: What is it?

In 2016, a team of researchers announced that the Tully Monster was a vertebrate—a primitive jawless fish related to modern lampreys. Case closed, right? Not so fast. Just a year later, another group of scientists published a rebuttal arguing it was definitely an invertebrate, closer to mollusks or worms.

To this day, science papers are regularly published throwing shade back and forth over whether this soft-bodied mystery had a backbone or not. The Tully Monster remains one of nature’s greatest cold cases.

4. From Muddy Fossil to Official State Symbol

Despite—or maybe because of—its utter weirdness, the people of Illinois embraced this bizarre creature. In 1989, Illinois officially designated the Tully Monster as its Official State Fossil. You can find its silhouette on moving vans, museum displays, and roadside signs across the state!

Adopt Your Very Own Prehistoric Mystery

The Tully Monster might be an unsolved scientific puzzle, but its surreal design has made it a legendary favorite among paleontology nerds, fossil collectors, and fans of the wonderfully weird.

If you want to own a piece of Earth's stranger history without needing a PhD to figure it out, check out this realistic tully monster stuffed animal plush toy.

It faithfully replicates that famous eye-bar, toothy proboscis, and shovel-tail in a soft, huggable form that's guaranteed to be the most unique plushie on your shelf!