Speculation exploded. Were they sea creatures? Exotic amphibians? Turns out, they were Arion rufus—red slugs—caught mid-mating in an incredibly rare moment few ever see. Red slugs are hermaphrodites, meaning they have both male and female organs. Their mating is a slow, coordinated dance of mutual fertilization that can last for hours—a fascinating, if slimy, spectacle of biology in action. Though...