Octoboo

Octoboos are ghostly creatures from the Boo family that appear in Super Mario Galaxy 2. They have rounded white bodies with pale blue spots, sporting yellow eyes, a short, pointed tail, and a bright blue antenna resembling a pom-pom. They also have circular, sucker-like mouths.

Appearing in the Haunty Halls and Boo Moon Galaxies, Octoboos can be found in groups and floating through set areas in a circular pattern. They serve as obstacles rather than enemies and cannot be defeated by Mario regardless of what power-ups he has. They can, however, be rendered transparent and intangible if Mario performs a Spin Attack against them or if Yoshi attempts to eat them.