What’s the weirdest thing you learned this week? The Weirdest Thing I Learned This Week hits Apple, Spotify, YouTube, and everywhere else you listen to podcasts every-other Wednesday morning. FACT: Male ratfish have retractable teeth growing out of their foreheadsBy Rachel FeltmanGhost sharks (also called chimaeras) are already weird. But the spotted ratfish takes things to another level with its forehead sex appendage. After analyzing the tissue, researchers discovered these are actual mouth teeth growing out of the forehead.