Hole in leather coral and necrotic flesh

[Bpones]

Came home tonight to my mix reef and saw a black patch on my leather finger. Attempted to brush it off and it became clear the black section was a thin membrane of dead flesh. Latter gently brushed away more of the dead area to see the extent of the affected area. I have no clue what could have caused this but was hopping someone could toss out ideas as to what this may be. Trying to include some images. Thanks everyone.

 

[Dkuhlmann]

I'd guess that you have some type of leather eating worm or nudibranch. Might want to Google it.

 

[Bpones]

The one thing that came across as odd to me was that there was not a hole originally till I attempted to brush away the black patch. I'll for sure see what I can find though. Thanks for your input.