They are small and light. All they need to do is detach from the rock and drift with the current. I do not beleive they have a Ffoot" to move with. They also reproduce very rapidly. It is difficult to remove them because if yoy injure the aiptasia and rupture any part of it its cellular materaial get in your tank and now you will have 5-10 more from removing the one. That is why they reach plague proportions. It is better to try to seal them in a crvice then it is to try to inject them or remove them. That is what is great about copperbands. If you get a healtyh one they will eat them. They can move quickly and can multiply rapidly. Ever seen that aiptasia tank at Greenwoods.