Pile Driver Micro-Goomba

Pile Driver Micro-Goombas, also parsed as Pile-driver Micro-Goombas and referred to as "fake bricks" by Fred Savage in the Celebrity Profiles section in the 9th issue of Nintendo Power, are a special variety of Mini Goomba that hides in a Brick Block. They appear in Super Mario Bros. 3 and its reissues.

Super Mario Bros. 3 / Super Mario Advance 4: Super Mario Bros. 3
Pile Driver Micro-Goombas first appear in World 2-1, the first area of Desert Land, and are a staple enemy in the various desert and sky levels throughout the rest of Super Mario Bros. 3. They are disguised as grounded bricks that can be distinguished by the fact that they do not glisten (except in Super Mario All-Stars, which gave them a light-colored outline instead, but this was changed back in Super Mario Advance 4: Super Mario Bros. 3). When Mario or Luigi approaches its brick, the Pile Driver Micro-Goomba moves slightly to show a pair of feet underneath the brick, then jumps high in the air and attempts to land on the plumber to damage him. These enemies are resistant to fireballs and can be defeated by stomping them, hitting them with a Raccoon tail, or tossing a Koopa Shell at them.

The Adventures of Super Mario Bros. 3
Although no Pile Driver Micro-Goombas appear, a group of Pile Driver Micro-Goomba-like blocks makes one small appearance in The Adventures of Super Mario Bros. 3, in the episode "A Toadally Magical Adventure." Although they have similar characteristics and looks as Pile Driver Micro-Goombas, they are real bricks brought to life and are referred to simply as "blocks." These blocks were created by Toad's pipe creatures after they rebelled against him.

NES Remix series
In NES Remix 2 and Ultimate NES Remix, Pile Driver Micro-Goombas, simply referred to as Mini Goombas, are featured as a Super Mario Bros. 3 challenge, where the player has to defeat three of them in World 2-1 within 20 seconds.