Circular red algae?

[sjs1949]

I have a forty gallon reef and fish tank. I recently cleaned off a lot of the green algae that was on the glass. I am now left with patches of a reddish hard algae (?).

What is it and do I want to get rid of it? How?

Thanks
S schwartz

 

[joy13]

Coraline comes in colors if it is hard to scrape off there is a good chance that is what it is.