Okosutobon (オコストボン,Okosutobon?) is a sea mine enemy from Mega Man 9 that is sleeping. If the player gets close or shoots at it, it will awake and follow him until it explodes. It appears in Splash Woman's stage and Wily Castle 2. It is invulnerable to almost any weapon, even Tornado Blow, but can be absorbed with a Black Hole Bomb.
Its behavior is very similar to an enemy named Scarfy in the Kirby series, although much more aggressive.