Yellow sponge?

I was cleaning my tank and I discovered this bright yellow slimy algae growing on some rocks. The rocks were at the bottom with little light. I seems to have spread quickly since I didn't notice it the last time I did a major cleaning. After some google research I found that it could maybe be a yellow sponge...any ideas?? yellow.jpg picture by mkubkowski - Photobucket

 

Its working now- very strange

Steve

 

Weird... maybe better to see what it looks like underwater?

- Mag.

 

Looks like a boring species of yellow sponge that will commonly grow encrusting as apposed to upward and outward. They literally coat an area much like cyano would. The growth pattern is usually restricted to the shaded areas and generally gains a bit of thickness.

If you don't want it then just do what you are doing in the picture and expose it to air. Do not scrub it in the tank. Any piece of sponge no matter how small will start a whole new area of growing


*Edit* found a link. The top picture in sponge Identification 10 looks similar to yours.
SpongeIDF 10