On the Bubble
From the Super Mario Wiki
The first part of the level is split into two segments: one features two Ziggies behind partial cover, and the other features three Ziggies behind full cover and a Hopper behind partial cover. Both segments are connected via a pipe.
The next part of the level introduces Chain Chomps as a stage hazard, and one particular Chain Chomp is stationed in the center, surrounded by a few Ziggies and Hoppers behind partial cover.