Gorgonia ventilana, Venus sea fan
Rare? Not sure, but I think so. I had to pester all the usual vendors for many years before one serendipitously showed up an a dealers tank (almost by accident). It's a Caribbean species where collection is heavily regulated. However it is proving to be fairly easy to grow - is photosynthetic and enjoys the same bright light high flow conditions that SPS enjoy.
Tech talk: Nikon D70s, Nikor 60mm Micro, 1/320s, f3.3