can you tell me what this is and if its a problem?

[enduringfate]

These white stringy strands just started growing on a live rock. Its in a shaded spot if that helps at all. looks kinda like an anenomy in structure but without the body, just kinda strands. Is this something common? So i need to remove it? I will try to upload a pic but it keeps failing..

[hotelbravo]

Google aiptasia and look at those photos if it resembles that in any way than remove that rock. Once out of your tank you can squirt boiling water on it to remove it. Do not disturb it when removing rock from tank as it can spew eggs