Finger Leather Coral Damage/Issue

[OctoPunk]

I have a Finger Leather Coral I have had for like four or five months. It has been thriving in my tank since I got it. No issue until now and it has even been growing by leaps and bounds.
At the base of each finger (on the inside - where the fingers meet the base of the coral) there appears to be multiple white craters. These craters started appearing about a month ago and the are becoming more prevalent as the days go by. Besides the craters nothing else seems to be wrong. The corals polyps come out like normal. It fully expands frequently and appears quite healthy expect for the craters white are getting larger and more frequent.
I have a Green Clown Goby who has taken up residence in it, but I really cannot see him eating this coral. That seems far fetched to me but What do you all think?
I also have a Starry Blenny who likes to dump sand on top of it, so every so often i have to blow off sand that collects in the base of the Finger Leather. Pretty much right were the craters are appearing, which I thought might be related? Thoughts?
Attached are the pictures of the coral and craters. Some said it could be the coral reproducing via division, but they did not elaborate on that or explain why they think that. Do ya'll think its that simple?

 

[Sakura2282]

I think is bleaching. I found this article that maybe can help you find out what's happening with your finger leather.

http://www.advancedaquarist.com/2002/2/coral

Bleaching Variation
Conditions can occur, however, that change the balanced symbiosis of algae and coral. Where there is chronic or acute nutrient limitation, the coral may not produce enough waste to sustain the zooxanthellae. Conversely, the zooxanthellae will not be able to produce enough photosynthate to sustain the coral. If the deficiency is great enough, the zooxanthellae density will be reduced. This can happen in three ways: the zooxanthellae will simply die and be ejected from the coral; the coral can digest the zooxanthellae for its own energy needs (if it is a species that can digest plant material, specifically cell wall components); or the coral can release some of the zooxanthellae from its tissues back into the water. This is bleaching.

 

[OctoPunk]

I was unaware that creating an indentation or crater in the coral was part of the bleaching process. I can see where people may think that because it is turning white in these areas, but the truly disturbing part is the loss of tissue associated with the crater. Someone also stated that it may be dying. no explanation past that of course. Could it be the coral is dividing/reproducing?

 

[Sakura2282]

I was unaware that creating an indentation or crater in the coral was part of the bleaching process. I can see where people may think that because it is turning white in these areas, but the truly disturbing part is the loss of tissue associated with the crater. Someone also stated that it may be dying. no explanation past that of course. Could it be the coral is dividing/reproducing?

I believe the zooxanthellae is dying on your coral and that's why it has those white craters on it, but I could be wrong I'm not an expert :unsure:. But, I don't believe the coral is reproducing though. You can ask @Aquarian, @MitchReef , @ZyberGoby , @ErinCahir, @RockStacker. I hope this mention will bring their attention to your post.

http://www.clearwatercampground.net/Corals_and_Frags.html

Finger Leather depends heavily on the symbiotic algae zooxanthellae that it hosts within its body.

The zooxanthellae draw energy from sunlight through the process of photosynthesis, which produces energy that is then delivered to the finger leather coral. Because access to light is crucial to perform photosynthesis, the finger leather corals will slowly move to adjust to more lighting.

The more access to light the finger leather coral is given, the brighter colored the coral appears. Secondarily, finger leather coral will obtain nutrients from micro plankton.

Reproduction: The finger leather coral is asexual, and reproduces through a process known as fission.

 

[Aquarian]

What are you running for lights?
What are your water perimeters?
How old is your tank?
How quickly is this spreading?

I had a finger do something similar with the craters but not the white spots. It's not reproducing, if it was you would see the fingers pulling away from each other until there was two stalks. There is something else going on it could be bacterial or a predator. Have you tried viewing your tank after lights out that is when most predators are active.

 

[Aquarian]

Take a look here this is pics of a finger leather coral predator to look for.
http://wetpixel.com/forums/index.php?showtopic=9714&hl=benthic+ctenophore

 

[Aquarian]

This is a rapa rapa snail which only comes out at night and only eats leather corals
http://www.saltcorner.com/AquariumLibrary/browsegroupspecies.php?GroupID=182

 

[RockStacker]

It does not looks like normal bleaching due to lights. Bleaching would more more widespread on the areas that were exposed to high light.

It looks like it could be getting stung by a neighbor.
Are there any other corals that are near it?

It could also be a coral predator as Aquarian has suggested.

Try to check the coral at night a few hours after the lights are off. Inspect with a flashlight and see if you can spot anything that could be picking on the surface of the coral.