2. Cicada 3301
This grisly practice has been in use since ancient times, and involves drilling a round hole in a patient's skull. Cave paintings from the Neolithic period show that people believed it would cure epileptic seizures, migraines, and mental disorders by letting out the "evil spirits" inside. Surprisingly, quite a few people survived the procedure and went on to live full, albeit draughty, lives with a hole in their head.
10. Toynbee tiles
13. The Radium Girls
In 1917, the harmful effects of radiation were still largely unknown, and radium was used as a glow-in-the-dark paint. The Radium Girls were watch-dial painters at the United States Radium factory in New Jersey. They were told that the paint was harmless, and so they would lick their paintbrushes to give them a fine point, which over time caused fatal radiation poisoning, anaemia, and horrific necrosis of the jaw.
These cryptic papers date back to 1885 and are written in a complex numerical cipher. They're said to contain the whereabouts of three tons of buried gold and silver treasure, originally hidden by a man named Thomas J Beale in a secret location in Virginia in the US. Only one text has been deciphered so far, but it only gave details of what was buried and its general location (Bedford County). Weird.
This tragic disaster is the largest non-nuclear explosion since records began, and is one of the deadliest industrial accidents of all time. On 16 April 1947, an arms carrier called the SS Grandcamp carrying 2,300 tons of highly volatile ammonium nitrate exploded after a fire on board. The blast leveled nearly 1,000 buildings on land, killed 531 people, and shot 6,350 tons of metal thousands of feet into the air.
18. The Bloop
The Bloop was a strange, extremely powerful low-frequency signal detected by the US National Oceanic and Atmospheric Administration (NOAA) in 1997. The sound varied in frequency, and could have been made by a large marine animal, but no animal on Earth is large enough to have created it. The NOAA now says it was probably caused by two large icebergs, but we all know the truth. It was Godzilla.