Our new anemone (pictured here: http://www.aquariumadvice.com/photopost/showphoto.php?photo=5485) has began to shrivel and seems to have changed color slightly (it has gotten darker). It has detached itself from the LR and has kind of just settled on the sand. Just hours ago, it was fine and fully bulbed. Should I be worried? I don't have any experience with anemone, this being our first one. Is this natural?