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Chuckoroks are a species of round, rock-like monsters seen only in Mario & Luigi: Superstar Saga.
Mario and Luigi encounter Chuckoroks on their search for the Beanstar Pieces, more specifically on their return to Chucklehuck Woods. Here, the Mario Bros. come to a small area inhabited solely by the Winkles and are eventually forced to enter Winkle Colosseum in order to receive the Beanstar piece. Inside the Colosseum, the brothers play a Chuckola Bounce minigame which finally pits them against the Chuckoroks, who move around in a circular motion and spit Chuckola Rocks at Mario and Luigi. Although these rocks can stun the Mario Bros. on contact, if the pair manages to make the Chuckola Rocks hit their Chuckola Board, they turn blue and go against their firers. As such, if the rocks hit a Chuckorok, they would knock the beast away and reward Mario and Luigi with a point. If the brothers catch a Barrier Mushroom, getting hit or manually firing their more-direct barrier at a Chuckorok would also make the creature explode. Although destroying some Chuckoroks, smaller ones would appear to replace them, making them harder to hit.
In Mario & Luigi: Superstar Saga + Bowser's Minions, the "X" on top of their heads are replaced by a giant swirl, and their eyes are completely black as their eyes will turn red upon spitting Chuckola Rocks or Barrier Mushrooms at Mario & Luigi. They are also seen as a 3D render rather than a 2D sprite.