Conger Eel
The conger eel is a species of marine eel that can be found in every ocean. They are usually grayish to blackish and have a large head, large gill slits and a wide mouth with strong teeth.
Being predators, they can attack humans and there have even been reported some cases where a diver was attacked by a conger eel.
The conger eel is an important food fish, especially in East Asia where it is often served as sushi.