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Thwomp Blocks are blocks appearing in Donkey Kong for the Game Boy. They first appear in Stage 2-8 on the Forest, and behave just like Thwomps, despite showing no signs of eyes or facial features. If Mario approaches them, they drop down and try to squish him. Mario can jump on them and use them as elevators. Thwomp Blocks can also squish Mario by pushing him against the ceiling.
Thwomp Blocks reappear in Mario vs. Donkey Kong, where they act almost exactly like they did in Donkey Kong. In this game, they keep smashing the ground regardless if Mario is below them.