According to Merriam-Webster, a cryptid is an animal "that has been claimed to exist but never proven to exist." But as Bigfoot believers and Loch Ness Monster enthusiasts are often quick to point out, it’s pretty difficult to prove that something doesn’t exist. Plus, it’s much more fun to indulge in the idea that giant sea monsters and hairy humanoids are roaming the uncharted corners of the planet.

On this episode of The List Show, Mental Floss editor-in-chief Erin McCarthy is taking viewers across time and space to unearth legends about lesser-known monsters that, again, haven’t been proven to not exist. Take the Mongolian death worm, a lamprey-like nightmare that supposedly lives in the Gobi Desert and radiates a poison so strong that you could die just by standing near it. If you’re an ill-behaved child or a Catholic who scarfs down steak every Friday during Lent, watch out for the Rougarou, a Louisiana-based werewolf that sniffs out those two demographics.

Learn about more fearsome, fascinating cryptids of all kinds in the video below, and subscribe to the Mental Floss YouTube channel for future episodes of The List Show.