I was fixing to say, a twenty gallon tank with that rock full of algae in it, would make a few hermit crab very happy. The first piece of live rock I ever bought looked like that, it was full of feather dusters, algae, micro and macro, I put it by itself in a ten gal tank with a compact florescent screw in 50/50 bulb, and put the tank in my work shop as a nano, could not get any work done because I was always staring at it. I had been a fresh water fanatic since I was ten, that piece of live rock converted me to salt water, I had never seen so much life in one piece or rock before. till this day it still amazes me when I go to feed my tank in the evening, I still find or see something new. welcome to a wonderful and addicting hobbie