Star Piece Cluster

The Star Crystal is a semi-common item in Super Mario Galaxy and Super Mario Galaxy 2 that consists of giant, blue Star Bits with strange spiky white crystal structures in them. They are most commonly seen floating in space directly in the path of a Launch Star. When Mario or Luigi fly through the path, they will smash right through the Giant Star Bit, releasing multiple separate Star Bits that will circle around them and can be collected with the Star Cursor until they land on the next planet.

In Super Mario Galaxy 2, Star Crystals can sometimes be found floating just above the ground, though this is extremely rare, as this will only happen during one level in the Melty Monster Galaxy. In this level, the Star Crystals will be destroyed if they are hit by Rock Mario or Rock Luigi. For some reason, these Star Crystals will only produce four Star Bits when broken. These Star Crystal can also be broken by the Co-Star Luma.

Three Star Crystals also appear on the Grand World Map, one near the end of World 1 and two at the beginning of World 2. The player can maneuver Starship Mario into these Star Crystals in order to break them and release the Star Bits inside. These Star Crystals appear to have a yellow spiky crystal inside them, and will release eight Star Bits when broken.

Trivia

 * In the Galaga Remix in Namco Museum Megamix, there are large floating objects in space that resemble Star Crystals. They award the player points.
 * Though they do appear quite frequently in both Super Mario Galaxy and Super Mario Galaxy 2, Star Crystals are far more common in Super Mario Galaxy 2 than in its predecessor.