Brown spot on Zoas. Something to worry about?

[gunit]

So these Blue Hornets were opening up nicely for weeks, but then closed off. All my other Zoas seem happy as can be so maybe it is something to do with the brown spot I see in this picture?

 

[joshporksandwich]

They look healthy but try dipping on revive or coral rx

 

[FL_Reefer]

They look healthy but try dipping on revive or coral rx

+1 on that

 

[Tenor]

Dip to clean the algae then try to make them happy again.

 

[PRomero]

Or just blow it off with a turkey baster, it's actually beneficial to blow off the corals and rocks once a week.