Maybe you read the series Animorphs—in which an alien gives a group of kids the power to turn into animals—when you were younger, or maybe you just noticed other, nerdier kids buying the books at your school's Scholastic book fair. Personally, I was one of those nerdier kids, intrigued by the book's still-terrifying bad guys, the Yeerks, who were super-intelligent parasitic slugs who controlled human brains by crawling into their ear canal. But even I didn't remember all the horrifying things that happened in these books, as pointed out by this viral Tumblr post: