Bacteria, Coraline algae, coral, Various algae and hitch hikers. The bacteria that colonize your live rock will aid in your nitrogen cycle and the breakdown of amonia, nitrite and nitrate.
Wow I actually sound like I have a clue with that statement!!
its all personal preference though if you like those rocks or not- most people prefer a rock thats been scrubbed and might only have a few hitchikers on it... with tampabays stuff you will get a TON of life, but also have the high probability of getting some bad Hitchikers like a mantis shrimp, etc..and the tank won't look as 'clean' as you see some people's tanks. but if you are going for a nice, natural looking tank this rock is amazing!