Hate to be the deliverer of bad news, but those are not Aiptasia , they are Majano Anemone and they are very BAD! I have a tank full, they wiped out my Coral. The only thing that I have seen eat them are Mat File fish. I wish I had Aiptasia like everyone said add some Peppermints and watch them disappear. Not with Majano they reproduce at an alarming rate. If you can find a File Fish ( Mat/Bristle Tail ) get one. I believe its too late for my tank I will have to do a total tare down on tank, sump. The brown are the worst.
Majano
Aiptasia