From the Super Mario Wiki
Star Crusters are creatures in Super Mario RPG: Legend of the Seven Stars. They appear in Bowser's Keep the second time it is visited, alongside much weaker creatures. Star Crusters seem to be a more powerful version of Crusties. Like Crusties, Star Crusters have extremely high physical attack and defense, but low magic stats. In battle, a Star Cruster will only use its normal attack on its own turns; if hit with a normal attack, however, they will immediately counter with a projectile that puts the attacker to Sleep. Though they seem to be crab-like, Star Crusters deny being crabs and seem to be especially offended when labeled as such.
Names in other languages
|Star Kānī, Kānī being the Japanese name of the Crusties