RFA moved, left tissue behind?

[Thub]

I've had my RFA for about 8 months, and it never moved, he's seemed happy the whole time, etc. The past month I've been battling a truly apocalyptic bubble algae problem using vibrant. Just a data point.
This morning, I noticed the water was cloudy before the lights came on, and once they did, I found a very gross looking spot where he used to be. Turns out he'd moved over a few inches to a new hole in the rock, but he left behind what looks like a fair amount of tissue. Is that normal? He's kinda closed up at the moment, but that's pretty normal on the morning.

 

[LesPoissons]

Not sure unfortunately, none of mine have ever left anything like that when they move. Id just keep an eye on him if he seems okay and maybe vacuum out the dead tissue/buildup.

 

[tankstudy]

I haven't confirmed what the ring is made of but I believe its mucous. If a RFA has been there for a long time, the mucus picks up all sorts of gunk over a period time and forms that ring. Generally doesn't form if a RFA has only been there for a brief time but if it's been there for a moment, you'll see it. It's kind of like shedded snake skin but just mucous. It's perfectly normal to see these.