Wild clam on my Christmas tree rock?? pic inside.
 

I have had this christmas tree rock now for about 2 months and last night I noticed what looks like a clam on the rock that closes everytime I shine a light on it. You can see it in the middle of the pick just below the blue sponge. It is slightly open. Is this a wild clam? oyster? What are the chances it will survive long term? It is about 2 times the size of a pea closed.

[IMG]http://i29.photobucket.com/albums/c277/sasscuba/100_0530.jpg[/IMG]

It's hard to see much detail, but it's most likely an ark clam. Most species stay pretty small. They're filter feeders and would probably benefit from some phytoplankton. I've had them live for a few years without supplemental feeding though.

Cool. Thanks.

About your Christmas tree rock. Can you tell me if the porites extend out of the rock or does it look smoth? Mine was "fuzzy" when I first got it and now the polyps do not come out. I don't think it is happy and am trying to figure out why. Any info you can give me on yours and what you do to keep the porites healthy would be appreciated.

[QUOTE][i]<a href=showthread.php?s=&postid=11506181#post11506181 target=_blank>Originally posted</a> by Crush Coral [/i]
[B]About your Christmas tree rock. Can you tell me if the porites extend out of the rock or does it look smoth? Mine was "fuzzy" when I first got it and now the polyps do not come out. I don't think it is happy and am trying to figure out why. Any info you can give me on yours and what you do to keep the porites healthy would be appreciated. [/B][/QUOTE]

My polyps come out mostly at night but are out on occasion in the day. My porites are brown and are textured but the new growth is green on the tips then goes brown. I have mine on the bottom of my 125 gallon in the front. My lights are HO T-5's with individual reflectors but I have 2 blue actinics in the front 2 slots. It gets medium flow and is doing awesome. Here is another pic. Any more questions, just ask. Only half my trees are out in this pic.

[IMG]http://i29.photobucket.com/albums/c277/sasscuba/100_0352.jpg[/IMG]

I have this shelled mollusk on the brown porites Xmas tree rock too - did not see any harm from it, no special feedings.

Just for fun - another, no visible shell, retractile mollusk on beige porites Xmas tree rock, was told, that it's bivalve:
[IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/black4.jpg[/IMG] [IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/black2.jpg[/IMG] [IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/10.jpg[/IMG]

Expended polyps:
IMHE, if the flow is not irritating and no chemicals are dripped it the stream nearby, polyps almost always are extended (you are feeding tank by the smallest food, right?):
[IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/2xJan17_07porit.jpg[/IMG]
up to this size in lower light place:
[IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/2XAug21macro.jpg[/IMG]

The greenish new growth kind extends less:
[IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/Xmas1Feb07greenish.jpg[/IMG]
again, more - in shaded area:
[IMG]http://i53.photobucket.com/albums/g78/dendro982/Christmas%20tree%20rock/Xmas1Feb07greenish2.jpg[/IMG]

My brown one closes polyps and, later, sheds the film, in case of harsh new water, or flow directed on it, or handling sometimes.

Do you know anything about what the beige (photo above) and pure green porites with wine colored worms require?
Have die-off on the first, and browning - on the second, after high Mg for bryopsis treatment and setting new light (same wattage).