Sweeper from Live Rock - What are they?

[catgirl29]

From day one, when I put any kind of food in the tank, these sweeper tentacles appear out of the tiniest crevices in the live rock and are very active. I see no discernible body of any critter. Does anyone know what they belong to?

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[jbadd99]

Hydroids. Relatively harmless but can tick a few corals off.

 

[willie1983]

jbadd99;1041356 wrote: Hydroids. Relatively harmless but can tick a few corals off.

I always wondered what those were i have alot of them thanks for the info