anyone know what this is?

[risk1994]

I got it as a single head now its splitting like crazy....

 

[Joevember]

Rhodactis mushroom

[Tired]

Yep, looks like a nice rhodactis. Might be one of the other shrooms, but it's definitely a mushroom corallimorph. It's very pretty! I love the contrast. Nice find. 

 

You may want to take precautions against it spreading too much, though. They can go a little rampant, and will usually win fights when they start to grow against another coral. May want to isolate the colony a bit, position things so it can't get too far onto your rockwork, unless you want a ton of 'em.