ID help please

[Longshank]

Are these snails, worms or something else? They are the width of pencil lead and at most 5/8" long. There are hundreds all over the rock. They grow on snail shells and the rear plastic overflow also. They are prickly and can be broken off easily. I think they grow right back. If the tank is stired up and really cloudy from rock replacement, the little tubes on the rock have a hair looking tentacle that extends about 2-3". Are these bad and is there any way to rid the tank of them? Thanks.
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[bobparker]

Vermetid snail
I wouldn't, worry to much about them except for the fact they are an indication of nitrates in the water, especially if they are multiplying like crazy.

[Longshank]

I've STFA and I think they're Vermetid snails but they seem bigger that what's in my tank and I haven't found a picture that looks excatly like these little tubes. They don't look good in the tank and could possibly irrate coral growing over them.

[noahm]

They respond to extra food in the water column. The strand you see is a sticky rope for catching food. They can irritate some corals if the strands are constantly hitting them, but they do not sting or hurt anything. They are generally a sign of overfeeding. Try and cut back a bit or get a better skimmer.

[Longshank]

They have been in the tank for a long time. My nitrate level is usually pretty low. I just tested it at 7 mg/L. Will a low nutrient level + low nitrate level rid them?

[noahm]

They generally don't thrive with less food. Nitrates really isn't the issue, but excess food is. I have several in my tank, but they are few and far between. You can super glue over the tube hole if you want, but if they aren't doing anything, don't start a battle just for the sake of it. That only leads to frustration.