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 invitation 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. At the end of the story, the five Sky Crystals formed a crystal Nintendo DS which contains the mini-game Triangle Twisters that the player can use at anytime after the credits.