What is this freebee

[nick654377]

So upon setting up our tank 2 months ago with live rock. With no lights for the first month. I started to see this guy growing. Had to break the rock to get a gorilla crab out and my wife said that thing isn’t going to grow. Well sure as **** it is growing but no clue what it is. It’s growing pretty good too. What could this be?

 

[dedragon]

i would guess blasto merletti, most likely the red outside with green centers variety