Roto-Disc
Roto-Discs are fireball-like entities that first appeared in Super Mario Land. However, they were not named 'Roto-Discs' until Super Mario Bros. 3. In Super Mario Bros. 3, Roto-Discs were found circling gray orbs, on which it was possible for Mario or Luigi to stand. In Super Mario Land, Roto-Discs would 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 was in the Mini-Mario course in Bowser's Castle in Mario & Luigi: Superstar Saga. As a throwback to the previous games, they were obstacles that could defeat Mario in one hit, sending him back to the beginning of the area.
