Stumbling upon a historic artifact that doesn’t have a clear history or explanation is always bound to bring out the conspiracy theorists, like that guy on the History Channel who will always tell you that it’s proof of aliens. However wild that may be, the truth is there are plenty of historical discoveries that experts just have no idea about, and while people have tried to explain them, they still can’t do anything but guess.

From the creepy snake-shaped mound in Ohio to the alleged treasure map on the Dead Sea Scrolls that even Nicolas Cage wouldn’t be able to decipher, let’s take a look at some ancient discoveries that no one can explain.