Yellow Stuff on Live Rock?

[sgc0286]

Hi! I got home from work today and noticed this yellow mark on my rock, It wasnt on there last night. It looks like yellow paint? Anyone know what it might be?

Here are a couple of pictures

 

[InfernoST]

Could be coralline algae. Does come off of the rock easy? If not it most likely is coralline.

 

[melosu58]

I have some yellow sponges in my tank. If it`s soft I`d say that`s what it is.

 

[sgc0286]

Okay Thanks. I havent touched it yet. I will soon and let you know.