Hmm... yeah, I'm not sure Orvin. Under a microscope the spaghetti worms that I've seen just look like small spaghetti worms. These could just be a smaller type though. I've also seen a giant spaghetti worm who's tentacles actually were the size of pasta spaghetti at the Waikiki Aquarium.
When moving around they'll look just like a thin worm or sometimes you can see the tentacles trailing behind the head like a mane.
The fact that you said that they're covering so many surfaces makes me think that they're flatworms. Spaghetti worms are hardly ever out of a hole in live rock or in substrate. The flatworms that I've seen are split-tailed like a chevron shape, reddish brown with a slightly lighter head and Anthony Calfo said that in Europe almost all flatworms in tanks there are pumpkin shaped. I hope they're not though.
-Rogue