The Crystal Stars are the 7 key items in Paper Mario: The Thousand-Year Door. They are used to open the Thousand Year Door beneath Rogueport. Each Crystal Star has its own special power that Mario can use to defeat enemies. Each star represents a precious stone, with the final one aptly made of crystal. The Crystal Stars were made by the Shadow Queen to help take over the Mushroom World. The four Legendary Heroes destroyed the Queen's body and imprisoned her spirit in her palace behind the Thousand Year Door with the help of the Crystal Stars. 1,000 years later everyone in the game are searching for them and Mario has the map. After all the events in the game Mario opens the Thousand Year Door with the Crystal Stars and uses them to defeat the Shadow Queen , whom possessed Princess Peach.