Fish in Coral

[Scales]

I bought a large birdsnest colony from Wendell yesterday. It had a crab and what looked like a shrimp (more like a small lobster) living in its branches. Today, it appears that there is also a fish in there ??? It is definitely not the crab or shrimp/lobster specimen...I am having trouble getting a good look at it...I suspect a picture will be impossible...all I can say is it has dark markings, almost black looking...it is tough to even comment on its body shape, but it looks more "round" than "elongated"...

I would like to ID it but acknowledge this may be impossible...anyone have any comments, specifically something along the lines of "it is an "X" because they are often found in (birdsnest) coral colonies"....Ok, I know I am being optimistic about this magical answer, but I thought I would try....

I will "turkeybaste" some food in there and see if I can get a better look tonight.