Mycobacteria? Something else?

Lost my betta fish last week to what I believe was graphite disease, a form of columnaris & a mycobacteria. I had just redone the whole tank to make it more “handicap friendly” for him and stripped it so it may have given it a chance to take hold.

Where he passed, this has grown. It looks similar to what was growing on his tail? Is there any shot someone could give a vague identification? Or a way I could identify it. I have access to a few labs, and am very friendly with my TAs and some professors, so its definitely possible I could talk to them about looking at it more closely.