Starbag

Yes, here it is. The one you've all been waiting for. The one none of you would ever recognize. But I'm telling you all right here, right now: It's a Starbag. They appear in sandy/dirty areas scattered around the levels of Super Mario Galaxy and Super Mario Galaxy 2. They are very elusive, as they are invisible, yes, invisible, for most of the time. By following its footprints (which it always leave behind) you can track it. When it realizes it's being tracked, it will run erratically. If you can catch up to it, and give it a Star Spin, it will be stunned, stop running, and become visible. If you can spin it a second time before it comes to, it will be defeated and release a whopping 20 Star Bits. Annoyingly, it respawns about 5 seconds later. If you are prone to impatience, don't try to get this guy immediately. But otherwise, it's a great way to get extra Star Bits.