Green Star

Green Stars, or Cosmic Jewls are items you collect in Super Mario Galaxy and Super Mario Galaxy 2. They are just like regular stars, as collecting them does count as beating a level. In Super Mario Galaxy, players usually collect them after they save Luigi on missions where you have to save Luigi. They can also be seen in other levels. In Super Mario Galaxy 2, after collecting 120 Power Stars and defeating Bowser, they will be hidden somewhere in all galaxies, and you can collect them to get 239 power stars and to unlock the Grandmaster Galaxy.