On a 10 day MC, I passed a crayon from grade school - just kidding. But during the Master-Cleanse I consumed no solids, but passed a hell of a lot of them. No Bentonite or that p-thing I can't spell. Just the lemonade and, yikes.
Got into colonics recently and passed a lot of black, rubbery stuff with light-colored "items" inside.
Not sure about the "Mucoid Plaque" black rubbery intestine-shaped halloween-type stuff per se, but I can assure you that you probably have a lot of crap that needs out. (no pun intended).