Sky Crystal

From the Super Mario Wiki

Sky Crystals are special objects in Mario Party DS. Five of them fall from the sky at the beginning of the Story Mode, and one lands near Mario. The next day, he shows it to his friends when the invtation to Bowser's party comes. When Mario and his friends get shrunk down from Bowser's Minimizer, he takes the Sky Crystal.

Eventually, the Sky Crystals are found in Wiggler's Garden, Toadette's Music Room, DK's Stone Statue, Kamek's Library, and Bowser's Pinball Machine. They all combine to become a game called Triangle Twisters.