Could be an Urban Myth - but you never know!
Read "The Journey to the Center of the Colon" at The Doctor Within site, linked below. (scroll to the bottom of the link below) But you just might want to read my boyfriends 1974 penny story first!
It's pretty fascinating - I just skimmed 'journey...' and I don't think it's in that article, but there is another of his articles that talks about autopsies and how they just blow the stuff out of one's colon (with chemicals and water...?) and out comes tons of mucoid plaque and worms (if you've ever checked out the parasite
forum it's pretty nuts how many people have them).
Anyway, The Doctor Within site is great....print it out and read!
Cleanses + The Doctor Within site link