The Boo Block is an item that was featured in Super Mario 3D Land: Fun with Friends for the first time. It's a white block with an open underside and Boo's face plastered on the sides.
When the player hits the block, he/she will "wear" it and become invisible for enemies. The block's effect is permanent and only disappears if the player gets hit by a stage hazard (Like spikes) or finishes the level.
- Super Mario 3D Land: Fun with Friends (Debut appearance)