(Okay, no, this is stupid. I'm not putting th-... Ugh.) A Rotten Mushroom is a "power-up", but in reality, it really isn't. It hurts you, like the Poison Mushroom does. But instead of following a direct path, it aims for you, jumps up blocks, jumps HIGHER if winged. All of this just to make you feel pain. (Can we please move on, now?)