Well, to update, I now have 91 stars, and my speculations was sadly correct. I guess I should put up a spoiler alert. So I just did. There you go. There are 100-coin stars. Except they are purple coins. It's the last kind of Trickster Comet, called the Purple Comet, and I don't believe they appear until you've beaten the game, so, Zion, it looks like you will have to go ahead and beat it before you get all 120 stars. In the early galaxies, they were deceptively simple. The one in Good Egg Galaxy was so easy that I temporarily pegged Purple Comets my favorite kinds of stars. But they get much worse as the game goes on. I'm stuck on one in the Toy Thing Galaxy, called Luigi's Purple Coins where you have to traverse a huge SMB-era sprite of Luigi (although not being at all similar to Luigi's color scheme from that game) made entirely of three different types of ground: platforms that disappear when you step on, platforms that start rotating when you step on them, and the rest is lethal dark matter. Oh, and you have a 3:00 time limit. Grr. I hate it. I hope they don't get any harder than that because it's just tear your hair out frustrating. If anybody's gotten this far... any advice?