sponge or something else?

[themericks]

Noticed this white thing encrusting on one of my corals and spreading onto the back wall of the tank from the frag rack the coral was on. It is slimy the the touch and has a pretty strong hold (gotta twist the frag to break the hold). Guessing it's a type of sponge I've never seen before, anyone know for sure?

 

[Timfish]

Looks like some kind of sponge to me.

Not to be critical but have you checked your PAR and water parameters? Your frags don't look that good.

 

[themericks]

Sponge it is then.

Test a few days ago, been stable like this for a while.

NO3: 8
PO4: 0.03
Alk: 8.2
Ca: 420
Mag: 1360
pH: 8.3
Salinity: 35

Dealing with a hair algae issue in display, recently dialed back par and started a refugium to outcompete it. Going slow but seems to be working, chaeto growing like mad, hair algae receding, also all established corals doing well, just some frags didn't like the reduction in par. Will bring it back up slowly. Thanks for your concern.