White mold?

[Xxflounderxx]

Hey guys I have a 40 gallon seahorse tank couple of zoas and soft corals. I noticed this white patch a few days ago any idea on what it is?

Temp 73f
Dkh 9.5
Nitrate 3
Phosphate .08

Calcium 427
I do dos nopox

 

[jerrod]

Looks like a sponge. It’s harmless.

 

[Idoc]

I'd guess a sponge as well.

 

[Tahoe61]

Sponge, harmless. Kind of cool.

 

[Xxflounderxx]

Sponge, harmless. Kind of cool.

Thanks guys