Any idea what this alage thing is?

[Fruichi]

I found this thing on live rock that I bought and I can't find what it could be. First, it kinda looked like regular red coralline algae but now it seems like some kind of macroalgae. It grows attached to the rock. Any idea what it is? Could it be harmful to the tank? Can I help it reproduce somehow? It looks really cool but it grows in the back of my tank...
Sorry if its obvious what it is but Im new to the hobby and I didn't find any red macro algae species that looked similar to this

 

[blaxsun]

Pretty sure it's macroalgae.