Mr. Egg is a non-hostile enemy in Abobo's Big Adventure.
He is a small egg enemy that originates from the arcade/NES game Burger Time.
In The Game
Like the Slime and the Eggplant Wizard, Mr. Egg is one of the few enemies who doesn't appear as a enemy in-game, though he only appears in the doorway in the Intro along with other possible NES characters. Aside from the Eggplant Wizard, the others are a Fireball, Birdo, Cut Man, and Duck Hunt Dog.