Hey George,
It's a Carnation Coral (Dendronephthya). It's a non-photosynthetic filter feeder. During the day it is quite small, about the size of a baseball.
Yes I would consider Coraline algae on PH to be a good thing until it starts to choke off the flow of water
J
I have seen Carnation corals at both J&L's and Hidden Reef. I know hidden Reef has two right now.