On one piece of live rock i have what i think is some kind of algae. It looks like bubble algae except it is red and not shiny like bubble. When i first got the rocjk i thought it was small mushrooms growing because it had some flat and wide parts that looked like mushroom. Then i got a tang (which i took back once i found out it would get to big for my 55) and he ate it so im guessing it must be some sort of algae.