From the Super Mario Wiki
This article is about the item. For information about the treasure from Wario World, see here
From Super Mario Bros. 2 (far left) and Paper Mario.
Crystal Balls are items that have been featured in many games throughout the Mario series. The first one is seen in Super Mario Bros. 2. Birdo spits it out after being defeated, and grabbing it opens the Hawkmouth to the next level. Years later, another one is seen in Paper Mario as the main magic tool for Merlon's family. There's also a red crystal ball, the Ultra Stone, for Ultra ranking Mario's partners. The Ultra Stone, as well as a standard Crystal Ball, is also seen with Merlon in Paper Mario: The Thousand-Year Door.
Madame Clairvoya uses one to see the future and other things in Luigi's Mansion. Another is used in Mario Party 6, in the Seer Terror minigame. Bowser uses it to see a player's "future," which usually is something bad. Occasionally, however, the player receives Coins or a Mushroom. All of this is just for fun, however, and has no effect on gameplay.
In Super Paper Mario, when Chapter 5 is complete, players can go see Merlee at Flopside. She claims that she wants her Crystal Ball back from Merluvlee, and wishes the player to go get it for her. After doing the task, Merlee rewarded the player with a key that opened a storehouse containing Piccolo the Pixl.
Also, Mini Marios are sold in Crystal Balls during the events of Mario vs. Donkey Kong.
Names in other languages
||Boule de Cristal