The Yonaguni Monument- Yonaguni Jima Island, Japan
Archaeologists can’t seem to agree on if the underwater monument is in fact man-made or a particularly complex natural form. If it is from an ancient civilization it would be the mark of a complex society of humans that existed somewhere between 5,000 and 10,000 years ago. The monument was discovered in 1986 and those who believe it to be a city structure think it sank into the sea after an earthquake about 2,000 years ago. Clues that lead scientists to think it’s man-made include sharp angles in the stones, cascading staircases and even potential cultural indicators like animal monuments around the structure.
Those who believe it’s simply natural argue that there are no perceptible seams in the sandstone, which makes them think that even the sharpest edging could still be the work of Mother Nature.