Thought to have lived over 300 million years ago, the Tully Monster looks like something out of a science fiction movie. But since its fossilised remains were discovered in Mazon Creek in Illinois in the 1950s, it was thought to be a small spineless blob with a weird mouth pincer from a bygone era. And we were right about most of those things.

However, in 2020, a new study finally revealed the Tully Monster (aka Tullimonstrum gregarium) was a vertebrate. That’s right: somewhere inside this squishy body was a backbone. That may not seem like a big deal for non-tully monster enthusiasts, but the enigma of Tully’s true evolutionary relationships has made this bizarre creature quite popular, ultimately leading it to be named the state fossil of Illinois.