The shape of the ancient worm might provoke a few giggles, but the carnivore's mouth is something out of a nightmare. According to the press release that accompanied the paper, the worm "could turn its mouth inside out to reveal a tooth-lined throat that looked like a cheese grater." You can see an animated version of this horror show thanks to the Royal Ontario Museum. In addition to being used for eating, the worm's teeth were also a way for it to get around. The weird animal was capable of digging the teeth into something and pulling the rest of its body to meet it.