Gnarly Granitemine is the first of ten unused levels. It is located in the unused World F, and takes place in a mine full of switches that eventually turns into a brick room with lava underneath with a huge spiky ball rolling towards you.
This level takes place in a cavern full of switches. In the first room, there are multiple switches that break bricks, of which some of them are traps. Taking down a pipe leads you down to a room made of bricks. A giant spiky ball rolls towards you and you need to be fast in this part or it will hit you. Eventually there will be Goombas which gradually get bigger and a shell to the left of them which can be used to hit all of them. The level eventually ends with floating bricks leading to the top of the flagpole. These will not be damage by the spiky ball.
- Star Coin 1: The first Star Coin is in plain sight but first you need to ground pound and make sure the blue switch palace is turned on.
- Star Coin 2: The second and final star coin also needs ground pounding but this time it is pointed by a down arrow. You have to avoid touching the huge spikey ball.
Due to the fact that the level is likely unfinished, there is only two star coins. However, after the checkpoint, there is an open square on the right side of the screen only accessible with the Penguin Suit. This is likely where the second Star Coin should have been at.