Well, the Boston Reefers link seemed to indicate that it isn't aiptasia. It does look quite similar to the picture, and it is likely the same species. I've had two of the specimans shown for about two months and they haven't moved from where they were on the rock.
By the way, the Bartholomea that I mention is in the Aiptasia family. (and I thought aiptasia was a genus) Not sure how Aiptasia are supposed to behave. If they start spreading out of control I have a bottle of conc. NaOH to work on their butts. It's the only thing I've found that works every time, but if you aren't real careful, it'll work on other things besides Aiptasia too.
I'm still bugged though. The corkscrew anemone in some pictures look like mine, in other pics they look nothing alike. I'll have to see if I can find a Periclemenes and see if he likes them.
Seapug, I've got rock anemones and they only have tentacles around the disk. This guy's oral disk is covered by the tentacles, especially when he retracts. I do love rock's though!