Roto-Disc

Roto-discs (also spelled Rotodiscs, Roto-Discs,  and Roto Discs   ), or simply Discs, are Fire-Bar-like obstacles that first appear in Super Mario Bros. 3. Roto-discs are found orbiting gray or red orbs, on which it is possible for Mario or Luigi to stand. Roto-discs are nearly invulnerable; they can be destroyed if Statue Mario lands on top of one. Duo-Roto-Discs can also be found, which consist of two Roto-discs circling the central orb. If the player destroys one, the other will disappear.

Aside from Super Mario Bros. 3 and its subsequent remakes, the only other appearance of Rotodiscs is in the Mini-Mario course in Bowser's Castle in Mario & Luigi: Superstar Saga and Mario & Luigi: Superstar Saga + Bowser's Minions. As a throwback to the previous games, they are obstacles that will send Mario back to the beginning of the area if they connect with him.

Super Mario Land contains Kaitensuru Honō, which are fiery orbs that similarly orbit a block and share the same attack pattern.

Super Mario Land 2: 6 Golden Coins also contains an enemy known as a Guruguri in the Mario Zone, which behaves in a similar fashion.

Trivia

 * In Wario's Woods for the SNES, after the player activates a combo, an energy orb appears and refills Birdo's time gauge. The sprite used for the orb is the same as the Roto-discs, only with a different palette.
 * A sign bearing "ROTO DISC" can be found in the 1993 Super Mario Bros. film. According to production designer, the Rotodiscs were imagined as the energy-conversion engines used in the electric Dinohattan cars.