Mystery polyps? Hydroids?

[damsels are not mean]

Just discovered these wavy things on my rock. Strange thing is I haven't added anything new to this particular tank in at least 5 or 6 years and the tank is up for 10 years now. Any idea what they are? Whatever they are, they had plenty of opportunity to grow like a weed and didn't, so I'm not very worried. Tried to get the best video I could, but they are far back in the tank and my lens is crap. Looked around and didn't see any more anywhere either.

 

[fish farmer]

Those look like hydroids to me. I had a patch of those in a 20 year old FOWLR tank and they didn't spread too far.

 

[vetteguy53081]

Video short and fuzzy as well as dark.
Could be colonial hydroids but could also be Yellow polyps

Yellow polyps:

 

[damsels are not mean]

Video short and fuzzy as well as dark.
Could be colonial hydroids but could also be Yellow polyps

Yellow polyps:

I thought about this too, but seems too small. They are like the size of acro polyps. Smaller than any zoanthids I have ever seen. If they do turn out to be yellow polyps I guess I can frag and sell them, heh.