[Van down by the river]

Hello Jim,
It's definitely not an algae, nor is it a gorgonian.
The picture is blurry, but it appears to be a small colonial polyp.
Probably in the Xenia or Clavularia family (maybe also a type of Hydroid). I've had it before. It doesn't appear to be very aggressive toward other corals but it does grow quickly.
It would be good for covering rock between larger corals. It would also be good for nano tanks or in a aquarium with decorator crabs.

oh yeah I'm back......