This is a strange glitch in World 3-6, where Raccoon Mario will temporarily be unable to break a Brick Block. Make sure you're not small at the part with an Ice Block on top of a Donut Lift and a Koopa Troopa on both the high and low platforms. Get to the lower platform, where a Brick Block containing a Super Leaf sits. Quickly kick the Koopa into the block or tail-attack the block to release the Super Leaf, then collect it. If all went well (timing seems to play a part in getting this to work), you should be able to hit the bottom of the Brick Block directly above you several times without breaking it.