Boost Block (Super Mario Advance 4: Super Mario Bros. 3)
From the Super Mario Wiki, the Mario encyclopedia
A Boost Block is a block used in Super Mario Advance 4: Super Mario Bros. 3. It appears in a single level of World-e: Castle Dash. When Mario is standing on a Boost Block, his Power Meter will charge much more quickly, allowing him to start running in a smaller space than usual.