What is my Yellow Fiji Leathers doing?

[Tremelle]

I have 3 Yellow Fiji Leathers in my 210 tank. I was walking pass the tank tonight and noticed something odd happening. The actinic lights were the only bulbs on at the time. There were a couple of stringy looking threads shooting out from each leather. The threads would extend out about 4" and then retract. They were doing this for awhile. I have a short video to show what was happening. Here is the link to the video, Threads from my Yellow Fiji Leathers. Does anyone have any ideas what is going on?

 

[tinyreef]

i didn't download the video but from your description i'd guess they might be the tentacles of comb jellies (aka ctenophores). try a google pic search of either term. they're often hitchhikers of sarcophytons for some reason (some unidentified commensal relationship?).