ID please

I'm still trying to figure out what this is. My local dentist told me I could take some stuff out of their tank. This was covering about 60% of his LR.
Sorry for the poor pic!

 

It's hard to tell from the pic. Any way you could get one that's a bit more in focus, perhaps a camera with "Macro" mode?

Does not look like an anemone, nor feather duster, nor sponge, so with those few narrowed down - still leaves a lot of options.

A better picture might help us out.

 

It looks just like green star polyps only brown.

 

That's what it looks like to me.

 

What is it called? Brown star polyps? Do I want that in my tank? Like I said his tank is literally covered with it.

 

It looks like a brown polylp, and sounds like GSP, overtaking a tank

 

Whats everyone's opinion, should I just keep the green star polyps and remove this brown one?

 

I would be patient and see at what rate it grows. I have gotten rock from friends with stuff that as you say was taking over their tank, but for whatever reason whether lighting, feeding, or just water levels (i.e. specific gravity, calcium, chemical levels) between tanks. My star polyps are healthy but very slowly spreading. So i would just watch and see, you can always remove it but once its gone you have to spend $ to get it back!!)