14. Wedge of Aiud
The wedge of Aiud was discovered in Aiud, Romania back in 1974, along with two large mastodon bones lying next to it.
From its proximity to the mastodon bones, the 5-pound wedge-shaped aluminum object is believed to be almost 11,000 years old.
This is astounding when you consider that metallic aluminum was effectively non-existent before the year 1825.
Of course, enthusiasts quickly proclaimed alien intervention saying that the piece might even be from an alien spacecraft that landed years ago.
This is a lot less wild than the theory that the wedge was transported back in time. However, the real origin of the wedge remains unknown.