This is a photosynthetic gorgonian. Probably belonging to the species Muriceopsis flavida which is known as the purple feather gorgonian or purple brush gorgonian.
I have acquired this specimen during a recent coral cutting workshop in a Marine Aquarium Society of Toronto meeting.
I don’t have a lot of experience keeping gorgonians and I have only picked up this frag because there were so many of them lying around during the workshop, so I have decided to give it a try. While this is supposed to be a photosynthetic gorgonian species the polyps do come out when there is something to eat in the water, so I can only conclude that this particular gorgonian coral still likes to eat.
Further readings and resources:
Live Corals: Sea Fans – Gorgonians
Purple Bush
The gorgonian aticle on Wikipedia.