Balloon (Super Mario Galaxy 2)
From the Super Mario Wiki
Balloons are rare items found only in Super Mario Galaxy 2. They look like multicolored party balloons with strings, and are always suspended in midair. They come in five different colors: red, blue, yellow, green and purple. Mario can pop them simply by touching them. When popped, the balloons will make a small popping noise, release five or six Star Bits, and then disappear. The Star Bits that are released from Balloons will home in on Mario if they are popped this way, so the player does not need to use the Star Cursor to collect them. Balloons can also be popped by shooting a Star Bit at them. If the player pops a Balloon this way, the Star Bits that are released will not home in on Mario, but will instead fall downwards.
Balloons are found solely in the Wild Glide Galaxy, the Fleet Glide Galaxy, the Tall Trunk Galaxy, and the Honeyhop Galaxy. In the former two galaxies, both of which Mario must glide through with Fluzzard, the player must steer Mario and Fluzzard towards the Balloons scattered throughout the galaxy to pop them and get retrieve the Star Bits inside them. In the Tall Trunk Galaxy, Balloons appear only in the galaxy's second mission, Tall Trunk's Big Slide. In this mission, they float above the slide at various intervals, and Mario must jump up at precisely the right time while sliding in order to pop them and collect the Star Bits inside. In the Honeyhop Galaxy, three Balloons are found hovering in the air over the gap between the Starting Planet and the Queen Bee Planet. While the player crosses the gap using Floaty Fluff, they can optionally pop the three Balloons and get some extra Star Bits along the way.