Pleuronectes rhumbus [now Scophthalmus rhombus] - The Brill
Like most flatfish, the brill has both eyes on the same side of its head, and it lives on the sea floor, with those eyes being the only exposed part of its body, allowing for effective ambush hunting, and hiding from predators.
Did you know that flatfish (the brill, flounder, sole, and their relatives) are actually born looking pretty normal? They have gas bladders for buoyancy, eyes on either side of the head, and are very non-flat. It's only as they mature that they become the odd-eyed, floor-dwelling, pancakes of fish that we know.
Which makes me wonder...what the hell was "Flounder" in The Little Mermaid? Even as larval specimens, flatfish aren't nearly that, er, rotund...
La Pèche et les Poissons; nouveau dictionnaire général des pêches. Henri de la Blanchère, 1868.