Need Help Identifying What This Is

[William Morris]

Growing on the face of just one rock. Not sure if it's a friend or foe.

 

[KJ]

Look like Ellisolandia elongata (red coralline algea).

 

[William Morris]

I think you are right. I tried blasting and picking it off the rock and it's painted on there.
So it seems like this is a good thing - a healthy tank will have coralline algae - I think

 

[KJ]

So it seems like this is a good thing - a healthy tank will have coralline algae - I think

Yes you are correct