All rays are born flat, perfectly symmetrical and appear to fly in the ocean as gracefully as any bird. Like sharks, they have no bones, they're cartilaginous. Boney flatfish, on the other hand, grow into their flatness. They are born bilateral, like most fish. But as they develop, their eyeball migrates from one side of their head to meet the other eye on the same side–making this animal the most asymmetrical vertebrate on earth. No wonder this perfectly streamlined cowtail stingray finds the halibut so distasteful.