The 52-hertz whale is an individual whale from an unidentified species that has been regularly detected since the 1980s. Nicknamed the world's loneliest whale, it is believed to be the only creature of its kind calling at a frequency of 52 hertz.

Alien hand syndrome is a rare neurological disorder that causes a person's hand to move without them being aware of it or being able to control it. It can occur after brain injury or when the two hemispheres of a person's brain have been surgically separated to treat epilepsy.

This list of poisonous plants is very helpful for avoiding accidental death, but could also provide a murderous individual with the perfect way to kill. The seeds in the castor oil plant below contain ricin, which is one of the world's most lethal toxins.

Named after a French author, Stendhal syndrome is a disorder which causes intense reactions when someone sees something they perceive as amazing, such as art. Symptoms include dizziness, fainting, rapid heartbeat, confusion, and hallucinations.

Paris syndrome happens when people visiting Paris experience extreme shock upon realizing that the city isn't what they expected it to be. They can go into delusional states and have hallucinations, anxiety, dizziness, paranoia, and increased heart rates.

The list of unexplained sounds contains six sounds detected by the National Oceanic and Atmospheric Administration that couldn't be identified at the time. Though four have since been explained, two named "upsweep" and "whistle" are still unidentified.

The list of inventors killed by their own inventions includes a number of unfortunate deaths, including that of Franz Reichelt, a tailor who died while testing his coat parachute. He jumped off of the Eiffel Tower.

According to a team of astronomers, "cosmic latte" is the color of our universe. After surveying the light colors of over 200,000 galaxies, they found a beige white to be the average.

The Sedlec Ossuary is a chapel in the Czech Republic that contains the bones of between 40,000 and 70,000 people, many of which are arranged as decorations. It even has a chandelier that is made up of every bone in the human body.

Bat bombs were used experimentally by the U.S. during World War II. Each held a hibernating bat inside with a timed incendiary bomb attached to it. When dropped, they deployed a parachute and opened to release the bats, which would then fly to buildings in Japan and start fires.

Trypophobia is the fear of irregular patterns or clusters of small holes or bumps. The brain is believed to associate these groupings with danger, as the holes look like those made by insects in fruit or skin wounds.

The Devil's Footprints refer to a strange phenomenon that happened in 1855, when trails of unidentified hoof prints appeared overnight in England and went on for up to 100 miles. Many believed these came from the Devil.

Sailing stones are rocks that seemingly move on their own, leaving long tracks behind them. However, this is caused by ice sheets on winter ponds breaking up and pushing the rocks as they are moved by the wind.

Unit 731 was a biological and chemical warfare research and development unit of the Imperial Japanese Army that horrifically experimented on human beings during World War II.

Visual release hallucinations, or Charles Bonnet syndrome, is when a partially or completely blind person experiences visual hallucinations, which crazily enough, sometimes fit with their surroundings.

Capgras delusion is a disorder which makes people believe that somebody close to them has been replaced by an identical impostor. It can show up in patients with paranoid schizophrenia and those who suffer from brain injuries or dementia.

Annabelle was featured in "The Conjuring" and "Annabelle," but she is a real doll kept in The Warrens' Occult Museum in Connecticut. A student nurse owned the doll in the 70s, but gave it to demonologists Ed and Lorraine Warren after becoming convinced that it was possessed by a demon.