This is a somewhat controversial coral, but all the same, well-loved for its extraordinary beauty. I bought two originally under the impression that they were very hardy corals (this was written in books and also some websites, including that of the online retailer I received mine from).
Since then, I have talked to fellow hobbyists and discovered that these corals are getting more and more difficult to raise in captivity. One theory is that corals are being collected from deeper waters now, and the ones that are being collected are of a subspecies that prefers lower light and different water conditions than are found in many reef tanks. I was told that anecdotally, it appears that the ones with the shorter, thicker and more purple tentacles seem to be of the older variety that did well, whereas the ones with the pinker and thinner tentacles have a poor survival record.
Though I can't confirm this has any real basis to it, I can say that my own personal experiences seem to support this observation, as out of my 2 elegance, the one that is still alive and kicking (the one shown above) is the purple tentacled one. The one with the thinner pink tentacles died after 2 weeks in the tank, though the fact that it was picked on incessantly by a yellow tang I had owned at the time does not escape my memory either. I have since sold the fish due in part to this annoying behavior. Incidentally, these corals, although entirely sessile, should be treated much like anemones; they should be fed regularly and kept at a distance from other corals, because they do have nematocysts (they can sting other animals and occasionally eat smaller ones).