Dr. Jensen has some info on this in his book. Jensen is an iridologist. David wolfe aouthor of Sundfood Diet Success System writes about mucoid plaque in his book and his website contains a lot of books that most definatley have information you are looking for, if these are not enough then id keep looking im interested as well, i have known this too that some dont believe it exists, whileothers including me who has done Bowel Cleanses has seen stuff come i out that was black and hardened unlike normal bowel movement material.
I would like to see this mad very public and the definite connection between mucoid plaque and its existence made. Shazzie.com also has her photographs of some plaque she has gotten out cleansing.