Plating algae/coral ID

[Armt350]

I've got some sort of plating growth in a couple of spots on live rock. It's a deep maroon with orange edging and appears to grow about 1mm per week.

It looks very cool and my initial guess is its a form of coraline algae. What do you think?

 

[ReefStable]

I would also lean that direction. Seems like a form of coraline algae to me.