I have been having trouble with the asterinas myself lately. I pluck every one that I see now, especially the ones that I see on my ZOAS(grrrrrrrrrrrrr). I have spaghettis too, but they seem to be confined to the sandbed, and I have very little down there, so I let them be. I also have seen what appears to be a small grey and white octopus(!) that I have no clue as to how it got in the tank. I haven't made any additions in a while, so it could have been there for God knows how long. I iwll try to get pics of it, it only shows itself at night. It pays to spend hours watching your tank at night in the dark with a tiny led flashlight...
Anyway, good luck with those spaghettis Dubs!!!