What is this in the shell of my brain coral

[ahl]

What is this bubble like stuff attached to my brain coral?

Thanks!

 

[rkpetersen]

Hard to see there, but if it's a shiny green bubble, it's probably Valonia bubble algae.
Can spread and become problematic, so best to remove.
Try to get it out without breaking it open.

 

[flchamp89]

I agree bubble algae. Look for others lol

 

[Biokabe]

If the coral wouldn't be stressed out too much, pull it out of the tank and remove the bubble in air rather than pulling it off in the water.

Bubble algae build up spores inside of the bubble, so if you pop them, out goes a bunch of spores to grow new bubble algae. Little issue if that happens in air, but could be an issue if it happens in your tank.

 

[rendosreef]

Looks like bubble algae and also maybe a black sponge. Remove the bubble algae and try not to break the skin when doing so.