Eric: In picture number 28 you claim the small blenny in the picture is the culprit of the white area below its tube. This is a planktonic feeding species of blenny, so I am not sure why you believe it is a corallivore. I have seen these fish many times and have never seen an area such as this around their "home". I don't think you can say this is the culprit unless you actually saw it doing the dirty deed.
JCD
JCD