Yes that is a mucus plaque. Take it and analyze it, and you will see. It is like "colapsed" Sausage skin, just with out the meat inside. It looks like a colon itself and it is made of mucus and a bit of fiber. Try stretching it, make it more widen you will see!
Take the gloves and check it out. I have been passing them for 10 days already and they usualy come out after enemas,..I thought it is nothing,...but decided to "investigate" a little bit more.