Well they're certainly not button polyps. You can see that the "skirt" on them has two levels to it. Button polyps have all of the "fringe" coming out of the button at the same place. The fringe doesn't alternate up and down like that (if anyone knows what I mean).
I still vote for aiptasia but I'm not adverse to saying they could be something else. If you're liking them that much, keep an eye on them. If another one pops up in less than 2 weeks, well, just imagine how many weeks it will take to cover that rock...and the rock next to it...and the rock next to it
Can you get a photo with less blue (ie. turn off your actinics) or is that just the light you have?