Crystal (Super Mario Galaxy)
From the Super Mario Wiki
During the introductory cut-scene of Super Mario Galaxy, the Airships are shown shooting crystal bits at Toads. In the opening of Super Mario Galaxy 2, they are seen dropping from the sky during Bowser's attack on the Mushroom Kingdom. Anything hit by the crystal bits is trapped in a Crystal, unable to move. Crystals have fairly weak structures and can be shattered in both games by a variety of attacks, including Mario's standard Spin, Fireballs, Green Shells and Red Shells, and Rock Mario's boulder attack.
Inside them are items such as Coins, 1-Up Mushrooms, and the occasional Launch Star or Life Mushroom. There are also octahedron crystals which contain only power-ups. Most of these crystals contain Star Bits; however, some may even contain Lumas or Toads, who help the player out once they are freed. Crystals sometimes contain enemies, namely Goombas. The quantity of Star Bits obtained averages from three to ten, and most of the Crystals found throughout the game contain four to six.
Additionally, there are large, rare Crystals that contain Power Stars. Large Item Crystals require two spins to be shattered.