HI, funny you should mention this- because I had the same thing in my bowel movements too!
It almost looked like clay too- more greyish than my regular feces-- but with the overlapping layers . It is definitely mucoid plaque. I only got about 7" of it out two times and that was it. I imagine that more is in there as our intestines are several feet long.
I didnt think it was mucoid plaque at the time, because pictures i've always seen of mucoid plaque always show black thin sausagy ropy stuff- this wasnt black, and it was rather thick and compacted.