A Blockhopper as seen in New Super Mario Bros.
Series Mario series
First game New Super Mario Bros.
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Blockhoppers(JP) are robotic creatures found in many desert levels in New Super Mario Bros.. They resemble Pile Driver Micro-Goombas from Super Mario Bros. 3, but are, as aforementioned, robots rather than Goombas. Also, contrary to the Pile Driver Micro-Goombas, they'll disguise themselves as both Brick Blocks and ? Blocks, posing much more of a threat to Mario and Luigi.

Interestingly, Blockhoppers will hop in tune with the music playing, much like the other enemies will dance to it. To know if a ? Block is a Blockhopper or not, Mario or Luigi must make sure to see if the question mark is moving or not. If it isn't, then it's a Blockhopper. To defeat a Blockhopper, Mario and Luigi must perform a Ground Pound from above it, throw a Koopa's shell at it, or run into it using the Blue Shell's Shell Dash ability. If Mario and Luigi Ground Pound the ? Block on a Blockhopper, they will receive either a coin or an item. If Mario and Luigi stand on top of a Blockhopper, it will hop in the direction they are facing.