 Help ID this worm
Hi folks,
Happy holidays to you all.
I need some help identifying this worm. I've done some searching but can't seem to find anything definitive. The worm is not unusual and I am certain it's quite common.
I'm just trying to determine it's name, what it eats, if it is reef tank safe, etc. Basically, should I keep him or not?
A photo is attached but here's a brief description. It's jelly-like and black. Segmented but depends on how much water it absorbs. When fully extended, about 12 inches in length and half-inch in diameter. It is covered with round "nodes" when fully inflated with water. The head looks somewhat like a feather star but the dark green "feathers" move individually like tenticles.
Thanks for your help.
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Started this tank Nov. 2004: 90 gal w/ overflow box, 2 x 150W 10,000k MH, 2 x 30W Actinics, sump, Tunze skimmer, Teco chiller, Iwaki pump, DIY stockman overflow. 30lbs LR, 30lbs base rock, 30lbs live sand, 3 damsels, rose bubble tip anenome, flowerpot (goniopora), bunch of unidentified shrimp | 
