Roto-Disc

Roto-Discs are fireball-like entities first appearing in Super Mario Land, but first named as such in Super Mario Bros. 3. In Super Mario Bros. 3, Roto-Discs are found circling gray orbs, which either Mario or Luigi can stand on, in Super Mario Land it would orbit a block; Roto-Discs are nearly indestructible, and can only be destroyed by having Mario or Luigi transform into a statue by using a Tanooki Suit and landing on top of a Roto-Disc as it orbits the central orb. Aside from Super Mario Bros. 3 and its subsequent remakes, the only other appearance of Roto-Discs was in the Mini-Mario course in Bowser's Castle in Mario & Luigi: Superstar Saga as obstacles that are capable of defeating Mario in one hit.