Re: gross question

I can remember a number of years ago when my gums were in pretty bad shape after not having my teeth cleaned for a few years. I ended up having a deep root cleaning
done by the hygenist and what was removed from under my gum lines was this black crud that looked like dark grits of sand. Maybe OPing is removing some similar exudate that was trapped under your gums and it is showing up in the toilet. My theory for what it is worth:)