Metal Box

The Metal Box (or green block) is a ! Block appearing in Super Mario 64. By breaking it, Mario is able to get the Metal Cap. The Cap Switch needed to turn on the Metal Boxes is located in the Cavern of the Metal Cap, a secret area inside Hazy Maze Cave.

The Metal Box also appears as an item in Super Smash Bros. Melee, and returns in all subsequent installments in the Super Smash Bros. series. Much like in Super Mario 64, this item causes characters to become coated in metal for a short period of time. Unlike in Super Mario 64, they have to simply grab the box to become metal, as opposed to jumping under it and causing the Metal Cap to emerge from it. They become heavier and fall faster, making it harder to directly KO them by blasting them away, but making it harder for them get back on the stage. Getting hit will cause the duration of the power-up to shorten. The Super Smash Bros. characters/forms Giga Bowser, Wario-Man, Mega Lucario, and Giga Mac are completely unaffected by Metal Boxes. Also, when a character becomes metal, their voice, for unknown reasons, is removed.

From Super Smash Bros. Melee onward until Super Smash Bros. Ultimate, each game of the Super Smash Bros. series has a trophy of the Metal Box. Interestingly, in Super Smash Bros. for Wii U, the trophy states the Metal Box appears in Super Mario 64 DS, but that game replaced the colored caps with multiple characters and their Power Flowers are all found in red ? Blocks.

The name "Metal Box" is unique to the Super Smash Bros. series.

Super Smash Bros. for Nintendo 3DS / Wii U
Blue indicates exclusive to the Wii U version.