Yes, sonja, but you are cutting your anems to physically make them that size...most people are not. Most BTA's that you get from the wild are not 1/2" long. Again, I am definitely not discounting that it could be a BTA, but it is more likely to be mojano, just by the pure and simple fact that BTA hitchhikers are so much less common and mojanos are everywhere...this is just most of the time that this is true...again, not saying this specific time it is true...
Sonja, you obviously know your anems pretty darn well to be propagating them. I'm sure after cutting an anem, it will retract and recess, but after it is fully developed, the chance of a small anem like that are the chances that that rock happened upon an RBTA spawn. In the wild, most BTA's are not going to be quarter sized unless brand spanking new.
I wonder where their rock came from...do you know where it was collected? That could be a very big indicator on whether it was a BTA or not.
Again, I really don't mean to be rude, I just don't want you to go through the same things that I and GSMGuy are going through with the mojano takeover...nothing that you would want to put into a reef will kill them...Butterflies or joe's juice...those are your options...not great one's either.
That is the only reason I hope you absolutely, positively know that it is a BTA. Trust me, if I was only here for myself or if I didn't care about other reefers, I wouldn't have said anything. I'm not trying to be a jerk or rain on your parade...if it is a BTA, then that is an awesome find and one of the coolest hitchhikers I've ever seen. I just honestly want to help people remove mistakes before they become problems...