What is this?

[wwidener]

I saw this white stuff in my tank last night. It is soft, almost mushy but stuck to the rock. Is it a fungus?

 

[NickNiz]

Looks like a goniopora to me.

 

[Tahoe61]

The white is just sponge. It should not be problematic and if it is a soft tooth brush to remove it will work well.

 

[Lovemyreef2015]

It's sponge. Harmless

 

[Macdaddynick1]

It looks like a white sponge or may be a bacterial mat , but your lobo coral looks like it got brown jelly disease, if that's so... that means it's dead. A few questions. What water do you use to do the water changes, is that new pump in the top of the screen on ? And what type of light do you use on this tank?

 

[Humblefish]

Agree with it being just a pineapple sponge