What is this coral??

[DragonStone]

It will grow in a toilet bowl if you add saltwater.
It’s one of the hardiest corals out there and can thrive in just about any setting - no special care required.
I’d get the algae off it, as that is only further hurting the coral.

With like a brush?

 

[Sharkbait19]

If using a brush, use a very soft one so as not to damage the coral. You can also try blowing on it with a turkey baster to see if that gets the algae off.

 

[Reefkeepers Archive]

If using a brush, use a very soft one so as not to damage the coral. You can also try blowing on it with a turkey baster to see if that gets the algae off.

Though make sure it's a clean turkey baster. Could also gently rub it off with a paper towel