Power star

A power star is what Mario/Luigi collect throughout the game. Each world contains 7 power stars. In super mario 64 DS, there are 8. Collecting a certain amount of stars will open up doors, revealing new worlds. You will earn a key to either the basement or the 3rd floor by defeating Bowser. There are 120 stars in the normal game, and 150 stars in super mario 64 DS.