This fish found in Europe's reefs 50 million years ago is an ancestor of modern flatfish like flounder and halibut. It had one eye on its head and one on its side, unlike flatfish today which have eyes on both sides. Scientists originally believed flatfish evolved their asymmetric eye placement gradually, but now know these ancient fish exhibited a genetic mutation that caused the rapid deformation of eye placement, and were over a foot long, larger than modern flounder.