Curious what are these?

[11purewater]

Sponges will die when exposed to air(but only the ones you want).but all sponges feed,If you have a high nutrient or older system they're just chowing down.Here's something I've done(if you have the means)pick off as much as you can, put the frag in your salt mixing container for a week(lit, heated, and circulating).The new salt water is essentially devoid of anything a sponge will feed on and should die off.Zoas will be fine.