Could someone tell me what this is

[deegrimes]

I have attached a picture to see if anyone could tell me what these long green stuff is growing on my lr. It is actually really nice the pic doesn't show it but it has other colors to would appreciate if someone could tell me. I had them before in my tank but never asked about them

 

[mudplayerx]

I had one of those living on a goniopora coral I had. It never harmed the coral so I wouldn't worry about it. It seems to be a filter feeder with no nematocysts.