Help with black patch on live rock

[caspervtx]

Hope someone can tell me what this is?
I have this "black patch" on what I call my Polyp rock. Its on the lower side and is "expanding." I've felt it and its softer than the rock but doesn't feel "spongy" to me in the sense you can push in on it. Seems to be, for want of a better word, a thin soft filmy sort of covering on the rock. Its generally black but has gray areas on it. And as I said the impression I get is its expanding/growing.
I have not been able to find anything like it where I've looked.
Any ideas?

 

[cranberry]

I can't really tell what I'm looking at in the pic, but black and kind of slimy to me means it could be a black tunicate... (Ascidia nigra).
Sometimes it looks like a black glob and you may or may not be able to see any siphons.
But if we are looking at the thing to the left... does it look black IRL? Doesn't really look black in the pic.

 

[caspervtx]

Originally Posted by Cranberry
http:///forum/post/3124880
But if we are looking at the thing to the left... does it look black IRL? Doesn't really look black in the pic.
Yes the thing to the left. Sorry about the pictures I'm still trying to convince my digital camera its an SLR and let me focus THROUGH the glass
I went and looked at it again using a flashlight. Its really hard to see as well because its on the lower side of the rock in shadow. BUT the black now that I really am looking closely and with your question in mind may be more due to what is beneath it. It is not a solid color. Where it does not appear "black" it almost appears to be a grayish color.
I uploaded three more pictures taken in different modes. They do much better justice to the "thing."
It does appear to be following the "valleys" of the rock as it expands as opposed to going up and over the entire rock.