Bouldergeist

Bouldergeist is a boss in the game Super Mario Galaxy. Its name is a portmanteau of boulder and poltergeist. It is the boss of the Ghostly Galaxy and is destroyed by Mario in battle.

Appearance
Bouldergeist is essentially a huge column of rocks roughly shaped into a face. However, its real form is a more extreme version of a Bomb Boo, with its tongue hanging from the bottom, like the tongue on a Bomb Boo being its weakness. It makes ghostly high pitch noises and explodes when defeated like a Bomb Boo as well. It has two enormous stone hands, which are used only in the second half of the battle. Bouldergeist's attacks include tossing rocks at Mario, summoning lines of stalagmites from the floor, and in the second half of the battle, slapping his hands on the ground and punching at Mario. It is fought in a plain circular arena.

Combat
This battle practices Mario's use of the Bomb Boo. To get Bomb Boos, Mario must dodge the black rocks that it throws at him. Once they hit the ground, they will turn into Bomb Boos. Each hit will gradually cause Bouldergeist to lose a bit of its stone layer. Three hits will completely destroy the entire stone layer surrounding Bouldergeist's real form. Once this happens, Mario has to, yet again, spin a Bomb Boo (that Bouldergeist conveniently leaves behind)at the shadow's red bubble to inflict more damage on Bouldergeist. However, the fight is not over, as Bouldergeist regains its old stone layer, and reveals its large rock hands. Bouldergeist then has a greater variety of attacks, as well as a larger form of protection. Mario can, however, destroy the hands the same way, but they regenerate after a short time, so Mario has to damage Bouldergeist before the hands reappear again. Mario must once again swing three Bomb Boos into it, and then swing one final Bomb Boo into its shadow form to defeat the malevolent stone creature and claim his Power Star. Also, in the second round, Bouldergeist may shoot golden rocks which reveal a coin.

Bouldergeist's attacks consist of a boulder throwing attack that Mario can only run from, and summoning a row of stone spikes out of the ground, indicated by dark shadows appearing where the spikes will. The rather delicate spikes will not harm the hero after they are out of the ground and can be broken with a spin attack. After the boss forms its hands, he has new attacks in addition to to the old ones. If Boldergeist draws back its fist, it is preparing to punch Mario. Boldergeist cannot change directions once it starts the attack so it is easily avoided and used to destroy any stone spikes. Bouldergeist can also use a slap attack that will crush Mario instantly if not dodged. A fair warning is given when Bouldergeist holds its hands over the surface of the planet before they drop. Also, Bouldergeist's stone spike attack forms two rows of spikes that Mario has to avoid. Bouldergeist's inner form is too weak to attack Mario. It may only flee.

Later, Mario must defeat it with one wedge of health under the Daredevil Comet to claim the spectre's second star. Bouldergeist will no longer throw golden rocks.

Bouldergeist does return in Super Mario Galaxy 2 in the Boss Blitz Galaxy as the fourth boss encountered. Its attack tactics are exactly the same as those in the prequel.

Trivia

 * The theme music while fighting Bouldergeist is the same as Kingfin's theme music.
 * Bouldergeist closely resembles Bogmire from Luigi's Mansion, as they have the same mouth and eyes. They are both ghosts, as well.
 * Bouldergeist is named after poltergeist, a very dangerous form of ghost who throws things, and in this case its tendency to throw boulders.