Piranha Plants on Ice, or Layer-Cake Desert-iceblock, is a secret level hidden in Layer-Cake Desert of New Super Mario Bros. U. Although this is a level in Layer-Cake Desert, the course is actually situated on a block of ice in Frosted Glacier to the right of the cake structure. To reveal this level, the player must locate the secret exit in Spike's Spouting Sands. Finishing this level unlocks a shortcut to Soda Jungle, skipping Frosted Glacier and Sparkling Waters.
The level begins near a segment where a row of Venus Fire Traps are found below slippery platforms, where they can melt Frozen Coins to make Ice Chunks fall. ? Blocks are found above the platform. Afterward, the player must cross a section of the level with a Koopa Troopa, as well as Venus Fire Traps that cause Ice Chunks to fall from above. The slippery platform can be used to obtain a 1-Up Mushroom from a Hidden Block. A Green Ring is then found, with the Green Coins appearing around Venus Fire Traps and more falling Ice Chunks. The player must cross over a row of Ice Chunks that Venus Fire Traps below can make fall, followed by more Ice Chunks that fall from above, some of which having Koopa Troopas on them. After two more Venus Fire Traps, the Goal Pole is found.
- Star Coin 1: Near the beginning of the course is a Warp Pipe. The player must reach it before the corresponding Ice Chunk blocks it to get the first Star Coin.
- Star Coin 2: Right before the first slope after the Green Ring, the player must use fallen Ice Chunks to reach a Warp Pipe in the sky that leads to the second Star Coin.
- Star Coin 3: The third Star Coin is found after a long series of floating Ice Chunks. The player must quickly dash across said Ice Chunks before their corresponding Frozen Coins melt to collect the Star Coin.