Definitely not Aptasia, color is off to be a Majano but I could be wrong, I've never had them in my tank. Before getting rid of it I'd let it grow out some more to see... could be some type of nem.
Definitely not, Pseudocorynactis and Corynactis both have a raised mouth in the center of the oral disk. Their polyps also feature fluorescence on the oral disk and and occasionally on parts of the tentacle but never the entire tentacle itself