Those things are actually scary in a non-scary way (if that makes sense).
They would probably be the scariest mobs in the game if implemented.
Did you see their behavior?
They float around their spawn point, endlessly patrolling above the murky swamp water, until the player goes near it.
Then it flies towards him and breathes green fire in a flamethrower-like fashion.
I'm not actually the creator of that particular mob, but I included the suggestion in my overhaul because it's awesome and the model is great.