There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
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The Platypus used to be considered a myth like Bigfoot and the Yeti.
18
The exact cause of death and burial site of Genghis Khan is unknown, because all of the 2000 funeral guests and 800 soldiers were killed in order to preserve the secret.
16
A waterfall known as The Devil's Kettle empties water into a hole and nobody knows where it ends up!
18