Bouldergeist is a boss in Super Mario Galaxy. Its name is a mix of the words"boulder" and "poltergeist". It is the boss of the Ghostly Galaxy. Bouldergeist is a large column of rocks shaped into a face. Its real form is a more extreme version of a Bomb Boo with its tongue hanging out of its mouth. Bouldergeist makes ghostly, high-pitched noises and explodes when defeated. Bouldergeist also has a special, strong-smelling, liquid in its mouth called Ghost Goo. Bouldergeist has two humongous, stone hands, but it only uses them in the second half of the battle. Bouldergeist attacks Mario by throwing boulders at him, summoning lines of stalagmites from the ground, and in the second half of the battle, slapping his hands on the ground and punching Mario. Bouldergeist is fought in a circular area with no hazards. The battle practices the use of Bomb Boos. Mario must dodge the black rocks Bouldergeist throws at him, and they will turn into Bomb Boos. Each hit will cause Bouldergeist to lose a bit of stone layer. Three hits will completely destroy Bouldergeist, showing his true form (see picture below). Mario must again spin a Bomb Boo to inflict more damage on Bouldergeist. However the battle is not over, Bouldergeist reveals his old, stone layer and stone hands. Bouldergeist then has a greater variety of attacks. Mario can destroy the hands, the same way, but as time passes they reappear. Mario must damage Bouldergeist before the hands reappear. Mario must spin three Bomb Boos at Bouldergeist, then spin another one at his red form to destroy him completely. Mario will then earn a Power Star. Bouldergeist may shoot golden rocks, which turn into Coin. Later Mario must defeat Bouldergeist again from a Daredevil Comet. During this battle, Mario only has one life, and Bouldergeist no longer throws golden coins. Bouldergeist also appears in Super Mario Galaxy 2 in the Boss Blitz Galaxy, acting the same way he did in Super Mario Galaxy.