Roto-Disc

Roto-Discs are fireball-like entities that first appeared in Super Mario Bros. 3. In this game, Roto-Discs are found circling gray orbs, on which it is possible for Mario or Luigi to stand. In Super Mario Land, very similar enemies that are possibly Roto-Discs orbit a block. Roto-Discs are nearly invulnerable. They can only be destroyed if Mario or Luigi transform into a statue by using a Tanooki Suit and land on top of one.

Aside from Super Mario Bros. 3 and its subsequent remakes, the only other appearance of Roto-Discs is in the Mini-Mario course in Bowser's Castle in Mario & Luigi: Superstar Saga. As a throwback to the previous games, they are obstacles that can defeat Mario in one hit, sending him back to the beginning of the area.