Spot on coral

[kaspm]

I know the picture isn't the greatest, however can someone tell me what the bubble looking area is on this.
http://i1024.photobucket.com/albums...D-0F53-490E-94E1-50F9A8FA8AB5_zpshg3zgf19.jpg

 

[cloak]

It's kind of hard to tell, but it looks like it might be an o2 bubble trapped in some algae.