Today's history's mystery is the Yonaguni Ruins. In 1986 or 1987, depending upon which source you believe, a diver discovered a stone formation under the sea near the Japanese island of Yonaguni Jima. It has been described as a pyramid, with tiered slabs going up for several levels.
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The reason this is a mystery is multi-fold. For one, experts cannot agree on whether it is man-made or natural. The nature of the stone is such that it has lines along which natural breaks can occur, removing slabs and creating a tiered look. However, the Japanese say they have discovered tool marks that make it look like it was man-made, and since the original discovery, they've found tools scattered along the floor of the ocean that are yet to be dated.
If the stone pyramid is man-made, they feel that it was created on land, then sunk during an earthquake, something they have many of in the area.
Much like the Tarim mummies of Xinjiang, if the Yonaguni ruins are man-made, it changes history as we know it. You see, they would have had to have been submerged in the last ice age, when no intelligent civilization was said to have existed in the east. A man-made structure such as this would indicate the west didn't have a monopoly on intelligent life.
There are both man-made and natural structures similar in makeup around the world, so until they can find a way to better study the Yonaguni ruins, they will remain one of history's mysteries.
What do you think? Man-made or natural? Is eastern history inaccurate?
May you find your Muse.