The Bob-ombs you encounter in this level can be used to help recover items, or break open blocks you otherwise couldn’t open safely.
The Mega Mushroom in this invisible ? Block can help you quickly clear away many obstacles in this area. It’s definitely worth using.
Green Star #1
Near the Warp Box leading away from the starting section is a set of large ? Blocks that, when hit, extend skyward. You can use these extensions as steps to reach another Mystery Box that takes you to a bonus room.
In the bonus room, you have 10 game seconds to reach the Green Star. Use the ? Blocks there to create a stairway leading up to it.
Stamp
The Stamp is in a small hidden alcove behind a Big Block, near the location of Green Star #1. You can access it without the Mega Mushroom so long as you’re big, then you can use a ground pound on the blocks. You can also break Big Blocks by using the GamePad touch screen.
Green Star #2
The second Green Star is inside a Rock Block not far from the Checkpoint Flag. You have to use a Bomb to blast it open. Be careful about how close you stand to the blast; it can take out the blocks surrounding your target and drop you into the abyss, if you’re not careful.
To eventually leave this place, you need to find five Key Coins. The first two are not far from the second Green Star’s location, near a pack of Chargin’ Chucks. Don’t ground pound the Big Blocks in the ground next to them. There’s nothing under them to break your fall!
Two more Key Coins can be found a little farther along from the first pair: One is in plain sight on the ground level, and the other is buried underneath small blocks to the left of a set of large ? Blocks.
The fifth Key Coin can be reached by using those ? Blocks to create a tower underneath it the Key Coin. You can do this easily by letting a Bob-omb walk into the blocks and explode.
Green Star #3
The last Green Star is behind a Baddie Box. Use Bob-ombs to blast the Big Blocks behind it, then explore the newly open ledge to find a ? Block that you can use to create a tower that leads up to the star.