Ocean Sunfish
Ocean sunfish, or molas, look like the invention of a mad scientist. Huge and flat, these silvery-gray fish have tiny mouths and big eyes that vanish into an even bigger body with a truncated tail. Topping out around 5,000 pounds, molas are the world’s heaviest bony fish. (This category doesn’t count sharks and rays. The whale shark is 10 times bigger.)
With their tank-like bodies, molas were clearly not built for life in the fast lane, but they hold their own against faster and flashier fishes and are able to live in almost all of the world's oceans. They are known to spend time near the ocean surface but tagging shows that molas are also prolific divers and migrate long distances at depth.