Star Piece Cluster
From the Super Mario Wiki, the Mario encyclopedia
Star Piece Clusters are semi-common items in Super Mario Galaxy and Super Mario Galaxy 2 that consist of big, blue Star Bits with strange spiky white crystal structures in them. They appear more often in Super Mario Galaxy 2 than in its predecessor. 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 Star Piece Cluster, 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 Piece Cluster Rocks 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 Piece Cluster Rocks will be destroyed if they are hit by Rock Mario or Rock Luigi. For some reason, Star Piece Cluster Rocks will only produce four Star Bits when broken. These clusters can also be broken by the Co-Star Luma's spin.
It is also possible to break a Star Piece Cluster using Mario or Luigi's Star Spin. To do this, they must go to Cloudy Court Galaxy, choose the first mission, grab a Cloud Flower, and traverse through until they reach the highest cymbal next to the Launch Star while having one carrying three clouds. At this point, there is a Star Piece Cluster in the Launch Star's path. The player must try to reach the Star Piece Cluster by creating clouds at the peak of their backward somersaults towards the Star Crystal. Even though the jumps may not be high enough, the last backward somersault can reach the Star Piece Cluster. At the peak of the last somersault, the player must Star Spin at the Star Piece Cluster; the Star Piece Cluster will break and Star Bits will follow the player.
Three Star Piece Clusters also appear on the 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 Piece Clusters in order to break them and release the Star Bits inside. These Star Piece Clusters appear to have a yellow spiky crystal inside them, and will release eight Star Bits when broken.