It's a varietal of a common Hawaiian. They come in all kinds of colors, shades of brown/tan/beige being the most common. You will, on rare occasions, see pinks and purples though.
Unfortunately, this particular one had a rather nasty encounter with a shrimp. We (LFS and I) didn't know the shrimp was not reef safe. It completely ignored my brown duster which had been in the tank for ~ 2 weeks prior to this one, but it savaged the pink one.
Needless to say, the shrimp is now gone.
I thought the duster was dead. About 3/4 of its tube was gone, lost its crown, etc. On a whim I left it in the tank. Lo and behold, it started gathering sand at its foot. So far so good - it's got about 1.5" of new tube started. No new crown yet, but it's only been a few days. It can take a week or two to regrow the "feather" and supplemental Iodine helps in the process.
I'm keeping my fingers crossed. Coming across that color is a rarity - not to mention it took me three weeks of LFS visits to figure out what tube it was in so I could get it...