1. There's a 1 in 3 chance police will never identify your killer if you're murdered in the US. Philly077 / Getty Images NPR reports that, "Criminologists estimate that at least 200,000 murders have gone unsolved since the 1960s." 2. There are over 250,000 deaths a year due to medical error. Sergey Tinyakov / Getty Images That's over 684 per day. 3. Over 80 million bacteria can be exchanged in one kiss. Hannatverdokhlib / Getty Images Those who are in a long-term relationship are more likely to have the same types of microbiota present in their mouths. 4. The air you breathe in a train station is 15% human skin. Hanohiki / Getty Images If you think leaving a train station will save you from inhaling skin, just know that about 80% of the floating specs you see in a sun beam are also skin. 5. Speaking of skin, you'll shed about 40 pounds of it in your lifetime. Andrey Prokhorov / Getty Images And your skin can shed at a rate of 500 million cells a day. 6. There's a jellyfish half the size of your pinkie that can kill you. Adam Calaitzis / Getty Images They're called Irukandji jellyfish, and they grow to be about a centimeter in body height. Jellyfish taxonomist Lisa Gershwin says that side-effects of their sting include pain that feels like someone is drilling through your back, sweats so bad that sheets have to be wrung out every 15 minutes, difficulty breathing, constant nausea and vomiting for up to 12 hours, and muscle restlessness to name a few. 7. And there's a brain-eating amoeba that lives in lakes and rivers of the southern United States. Romrodinka / Getty Images The single-celled organism travels up the nose to the brain, where it starts to break down the tissues. 8. Thomas Hargrove, a homicide archivist, estimates that there are over 2,000 serial killers at large right now. Coldsnowstorm / Getty Images According to his records, there are over 27,000 murders that aren't even in FBI files. 9. 20% of children report hearing voices. Techin24 / Getty Images Having an imaginary friend may be a child's explanation for hearing these voices. 10. If the sun exploded right now, you wouldn't know about it for another eight minutes. Kagankiris / Getty Images The energy from the explosion would be traveling at the speed of light, which means it would take eight minutes and 20 seconds to travel from the sun to the Earth. 11. Botflies are a type of insect whose larvae burrow under your skin. Erikkarits / Getty Images During that time, you can see them move around underneath your flesh. 12. Horned toads can squirt blood out of their eyes. Tap to play or pause GIF Tap to play or pause GIF National Geographic It's a very helpful way to get debris out of their eye. 13. Oh, and some moths drink human blood. Ilia Ustyantsev / Via commons.wikimedia.org Vampire moths feed on the blood of mammals, including humans. They can suck blood for up to 50 minutes. 14. When you die, your house cat is going to want to eat you. Viktor_gladkov / Getty Images And if your cat doesn't, your gut flora might start taking over your body and colonizing your internal organs. 15. Speaking of disturbing pet facts, dogs like squeaky toys because they mimic the screams of their prey. Devin Mcmiller / Getty Images There's a theory that they rip the squeaker out of the toy because as long as it squeaks, the dog still thinks it's alive. 16. The dead outnumber the living 15 to 1. Ysbrand Cosijn / Getty Images In 1968, the dead outnumbered the living roughly 29 to1. 17. Fresh urine is cleaner than spit. Ocskaymark / Getty Images Your pee has about 100,000 bacteria per ml, while your mouth has around 100 million bacteria per ml. 18. You swallow one to two cups of mucus every day. Terri Rosa Fox / Getty Images That's over 22 gallons a year! 19. On average, you secrete 26 gallons of sweat into your bed per year. Demaerre / Getty Images Which means you sweat a little over one cup per day on average. 20. The average bed has between 100,000 and 10 million dust mites. Selvanegra / Getty Images But don't worry, they just want to eat your dead skin. 21. Finally, 20% of coffee mugs have traces of fecal matter on them. Photoboyko / Getty Images In addition, 90% of coffee mugs are covered in germs.