My alveopora has not been extending fully the last week or so.  I was just looking at my tank when the lights went out and noticed a couple things.  First, my emerald crab was hanging out under the tenticles.  Could he be irritating the alveopora?

Second, I noticed a large patch that looks similar to a sponge right up and touching the alveopora.  A picture is worth a thousand words, so while the lights are out I snapped one.  Notice the yellowish patch that I've circled.  It's starting to encroach on the coral.  Do you think this could be causing a problem?  Should I move the coral?

Probably sponge, probably encroaching, probably good, definately something I wouldn't worry about.

Adam

Moving it just a half inch wouldn't hurt and would get it away from a competitor.

Any other changes in your tank recently, like temperature, light, feeding, etc?

Thanks both for the replies...

Yes, I've made a lighting change.  I replaced my 36 watt PC atinic with two 75 watt VHO atinics about two weeks ago.  It just been my experience with this alveopora that it doesn't take much at all to get it to recede, which had me wondering about the crab.  And I understand some sponges can be very "aggressive" chemically.  I really like where it's placed, so I might wait a week or so more and if he doesn't get better, I'll move him.

That's a major increase in light. It doensn't bother our eyes, but my guess is that is a 300% increase in the 420nm wavelength which is a real shocker to the coral.

Also, the coral may be sensitive to minor changes of other parameters because it's bothered by the yellow sponge (or something else in the tank). My guess is that a move many inches away from the sponge and other coral could be just what the Dr. ordered! If that doesn't do it then it may be the crab you spoke of or some other coral in your small closed system.

Barbara, the person I visited last night has a huge anemone that rules the roost in her 55. It is more than a foot in diameter not including tentacles, so not a lot of things can live in the tank with it because of bio-chemical warfare! I wish I had my camera.

I had a similar experience with my goneopora (that spelled right?).  Had him a week or so and he was doing fine.  Then I added my 2 110w VHO Actinics and he shrunk up quite a bit.  I had to put him under an overhang, now he seems to be doing alot better.

Troy

I think Mark's right.  I moved the coral down on the sand under an overhang and it seems to be doing better.