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The shake block is a type of block that appears in the game Wario Land: Shake It!. They are blocks with the Shake King's face that come in blue and red varieties. At first, blue shake blocks will be transparent with dashed lines bordering the block, while red shake blocks will be fully solid. However, once Wario frees a Merfle from its cage, all blue shake blocks will become solid and all red shake blocks will turn transparent during the incident.
Blue shake blocks tend to be placed in areas that Wario cannot re-enter, which means that he will have to find an alternate path to get back to the level entrance. In contrast, red shake blocks tend to be placed in areas that Wario cannot access right away. Most of the time, he has to free a Merfle in order to gain access to areas blocked by these blocks. Red shake blocks tend to keep Wario from making shortcuts to the Merfle cage, but once he frees the Merfle, Wario can use the shortcuts to get back to the level entrance and can also find treasures that have been previously blocked by the blocks.
Shake blocks are functionally identical to the Kaeru Blocks of Wario Land 4, differing only in aesthetic. They also work with the unused switch, and are even internally named after the original blocks.