Green Power Star, MarioWiki

Green Power Stars, (or simply known just as Green Stars), are a special type of Power Star first found in Super Mario Galaxy. These power stars are very rare and typically appear under the shadow of the Green Comet, they also appear hidden in certain levels and must be found as a normal Power Star, typically, when all the Green Stars are found, hidden Galaxies are discovered. Green Power Stars are shaped like standard Power Stars. Hence the name, they are colored green. In the Super Mario Galaxy

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Green Power Star, MarioWiki

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