Hedron

The Hedron is an obstacle in Super Paper Mario. It is encountered in the Outer Limits. The Hedron is an indestructible, rotating, blue rectangle with a yellow outline. If the player is hit by it, they take damage. Hedrons are often encountered in groups, with quick, evasive maneuvers being required to avoid them. Flipping to 3D does not help, either, as the Hedron exists in the third dimension as well.

Trivia

 * The Hedron's name comes from a geometry suffix.