ive had at least two for the last seven years. up til recently, i had four in my 60 gallon. two of them just became massive, with one overpowering the others. they are an ornery anemone and while the largest planted itself and never moved, the others continually tried to attach on top of each other or push the others off their top spot. even though, to me, there was plenty of other optimal sites to attach. i also found that the dominant one will look great: full base, huge spread with thick tentacles. the less dominant ones remain smaller with thinner tentacles. i realize it doesnt sound like im talking about anemones, but its a phenomenon ive noticed in two separate systems now. i dont know if its something the larger anemone puts in the water or what, but even being the same species i think they can be just as aggressive as the fish they host.