Is this a sponge?

[Lavey29]

This is a nighttime picture with flashlight. The yellow critter in the back right portion of the picture. Is this a large sponge or something?

 

[blaxsun]

Looks like a sponge, yes.

 

[Lavey29]

Looks like a sponge, yes.

How big do they get in the tank. This is about 2 inches now.

 

[Sean Clark]

I am not seeing it. Back right and yellow?

 

[Sean Clark]

The mushroom?

 

[Lavey29]

I am not seeing it. Back right and yellow?

Yes top right, it's not a mushroom. Has a hard feel tonit.

 

[Sean Clark]

Hmmm

 

[Lavey29]

Hmmm

It's under a rock cave and gets no light from the tank.

 

[Sean Clark]

It's under a rock cave and gets no light from the tank.

The vibrant coloration is what I am stuck on.

 

[Lavey29]

The vibrant coloration is what I am stuck on.

It's a whitish yellow but the flashlight illuminates it

 

[blaxsun]

It's a whitish yellow but the flashlight illuminates it

It looks like many of the sponge colonies on the undersides of my rocks.