I have had my fair share of aiptasia, so I know exactly what that looks like. This thing looks very different from regular aiptasia. Unless of course there are different species of aiptasia then maybe. I will see if I can get a close up picture when it comes back out tonight. I admit, in the pictures I have on here already it does look like aiptasia, but up close is a different story. I will probably try to kill it with some type of aiptasia killer, either that calcium hydroxide or joes juice.