Sponge thing in zoas

[boxed_reef]

I have some sort of sponge like thing growing in some zoas. What is it? And how do i permanently get rid of it? A couple months ago I manually removed it and did a 50/50 peroxide dip... and now it’s back. I just removed it again and dipped in revive. It causes the zoas to close up, how do i keep it from coming back?

 

[reef lover]

Since it grew back already I would try and area with more flow most sponges don' t like high flow.