What is this?

[Cathy Theriault]

It appears like a slim attached to the live rock. It has some pertruding clear bubbles. It has spread slowly....

 

[Dan I]

Looks like a sponge to me. Is it white or an off-white color?

 

[Cathy Theriault]

Off white, has a hint of green

 

[Untamedrose]

encrusting sponge.

 

[Cathy Theriault]

encrusting sponge.

Is it safe to leave it?

 

[Untamedrose]

totally all sponges are filter feeds and harmless

 

[Cathy Theriault]

Thank you!

 

[Dan I]

Yeah, a sponge is good to have to help filter the water. I usually get my sponges in my sump.

 

[TheLadyCrash]

encrusting sponge.

+1