Drop Blocks
From SmashWiki, the Super Smash Bros. wiki
The Drop Block (analogous to the Donut Lift that first appeared in Super Mario Bros. 3) is a part usable in Brawl's Stage Builder, and are also found in later levels of the Subspace Emissary. In this mode, they fall faster and often have collectibles, such as stickers or trophies, placed on top of them for the player to grab while trying not to fall with the blocks. In Stage Builder, they are brown blocks with dark brown upside-down triangles on the sides. When stepped on for long enough by characters or items, these blocks shake, then fall. They eventually reappear. They only drop when they are stood on, so it is possible to make one way passages by sealing a narrow entry with a Drop Block. Drop Blocks also appear in certain levels of the Subspace Emissary. Interestingly, it is possible to Wall Cling to the side of a Drop Block without making it fall.
