There is a 600 year old 240 paged book called the Voynich Manuscript, that’s written language is still completely unknown today.
15
In 1987, a Chicago TV station had its broadcast interrupted by a pirate signal that shows a man in a Max Headroom mask mumbling and being spanked with a fly swatter. Despite investigations by the FCC and FBI, this became the only known incident in which a hacker interrupted a major TV broadcast without getting caught.
19
The Platypus used to be considered a myth like Bigfoot and the Yeti.
18
There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
23
Since 1982, a radio frequency emanating from Russia has been broadcasting a buzzer-like sound and, periodically, an unknown voice reads orders, names, and numbers. No one knows where exactly it is coming from or what it means.
13
There is a mysterious and loud radio signal known as 'the space roar' that has yet to be explained.
15