31. Roman Dodecahedron
This one’s a little weird. Most of these finds remain mysterious because the people who created them were wiped out for one reason or another. But the Dodecahedron was something that was made by Romans, whose mark on the planet and the history of mankind was hardly erased from the books.
And yet here we are with the Dodecahedron, an object that is littered throughout the vast Roman Empire that spanned an entire continent, and yet we have found absolutely no historical reference to it. Just like the Voynich Manuscript, about every year someone comes out and says they “solved” the mystery.