Need help with ID

[Chrisz]

This started growing in my tank over the last couple of months(purple thing in center of picture), I am guessing some kind of birds nest? It grows really slow it is now about the size of a dime and is hard, any guesses?

 

[fort384]

Is it hard, like an SPS? Can you see any polyps on it?

 

[dmorrison]

looks like a branching coraline algae

 

[Chrisz]

It is hard and I can not see any polyps. I did not know there was such thing as branching coraline algae. I will have to research that one. Is this something common?

 

[SeahorseKeeper]

I am thinking branching coraline as well.