Over the last few decades, the planet has been at the mercy of a ten-legged, many-clawed crustacean ravenously creating a clone army bent on world domination. No, it isn’t an interplanetary interloper or the result of an uncontained government experiment. This is biology gone wrong, or if you happen to be a marbled crayfish, biology gone horribly right. What’s unusual is that instead of the expected two copies of their chromosomes, marbled crayfish have three. Their genetic composition is similar to the Slough crayfish, a close relative, leading scientists to conclude that the first marbled crayfish was born through an...