There are alot of different colors of real coral (real coral, not live--you know dead but still real). I can't say I have seen much yellow, but red and blue are very popular along with the hundred different types of white at my lfs and are intended for your tank. They can also help boost ph just as cc does.
I hope this is the kind of coral you're talking about.
Great addition to the fo tank, but needs to be cleaned.
Good Luck