Christmas Tree Worms & Porites

[cdylnicki]

A question regarding my Christmas tree worms (CTW) and the porites coral.

My CTW are doing wonderfully, but my porites coral seems to go through 3 stages.  First it looks "normal", then the brown coral stick high out of their pores, and finally the casing of the coral seems to be turning green yet the heads of the porites coral seems to be getting smaller and seem to disappear into their pores.

Is the coral body supposed to turn green? 

Any ideas? 

Below are my 2 different CTW rocks - the latter one is looking a bit sad as I had a rough move back in early March. 

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[Tyler.L]

what lighting is it under?

porites is an sps so if it is under unacceptable lighting it will die but i do not know what will happen to the ctw as i have no clue how they benefit from the porites.

the second picture is 100% dead sps skeleton and its green algea that has grown on it

[Vincenzo.]

normally the worms (trees) will all die off in 6months from starvation...they need to be fed 3 times a day. if your using green-water thats always good. they also do well in a large system. they are interesting critters.. g'luck with them

[cdylnicki]

I've had the below coral since August 2009 (the one that is "100% dead sps skeleton and its green algea that has grown on it".

Its hard to see in the first pict, but there are sections in this coral where the porites have come back.  STORY TIME: I had a bad moving experience back in March where my tank heated to over 90 (It moved from an 9th floor apartment -no heater necessary to a tank in the basement of a 70's built house).  My apparently great Eheim heater decided to malfunction and as I was busy moving between 2 places, did not get a chance to notice for around 20 hours.  Thankfully that and my mandarin dragonettes survived, while I had a loss of my 5 seahorses (their original setup can be seen in my profile pict).  You can see the CTW coral in the middle of this tank as well.

I've posted some updated picts and have posted below.

Back to my original question(s): You can really see in the below photos when the hermit crab walks the sizes of the coral and the polyps retract to safety (I've drawn arrows to show where the green is spreading).  Is this some sort of Coraline algae that only grows along with this coral?  Is it a threat? Eg. will it grow so thick it blocks the polyps from extracting?  Or is this some helpful form of protection for the colony.  Why does this appear only within these specific polyp colonies or are there other polyps that have a similar occurrence? 

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