Help me ID this hitchhiker

[Lenny66]

They appeared on a frag about 3 months ago and have spread all over my 20gal nano. They have a brown tube and white fan shaped head. They don't sting my hand, but they catch food from the water column. Some are clustered up and others are spread out. Any help would be appreciated. The fan is barely visible to the naked eye. I don't think they are fan worms as prazi had no effect on them. My guess is hydriods. :sad2:

The photos are 2-5 times magnified on an iPhone.

 

[Lenny66]

I forgot to add that they do not sting me when i touch them.

 

[mndfreeze]

Look like hydroids to me but there are a LOT of weird little critters that grow in a similar fashion and shape. I have some colonial hydroids in my tank that look like little stalks but the "head" end of it looks more like a puffball/dandelion. They are so small its hard to tell if the stalk is tube like or not though.