Armored Mud Ball

I just learned over the last year what armored mud balls were (balls of mud that are rolled by moving water over stones, which stick to the surfaces of the balls) and how they have been found associated with the Kankakee torrent here in Illinois: http://books.google.com/books?id=cPfw7aIlowIC&pg=PA158&lpg=PA158&dq=armored+mud+ball+kankakee+torrent&source=bl&ots=Rp44nRB-4p&sig=8cV05df3PEM_MenwDzPRPgllykA&hl=en&sa=X&ei=a4URUpbsGaWIyAH9v4HICw&ved=0CC0Q6AEwAA#v=onepage&q=armored%20mud%20ball%20kankakee%20torrent&f=false.

I was surprised to find an armored mud ball, presumably recently made, in a creek bed in Bartonville where I was fossil hunting.  I saw a recipe for making a food analogy of the mud balls that was published by the National Park Service: http://www.nps.gov/badl/forkids/upload/Make%20an%20Armored%20Mud%20Ball.pdf.  I am reminded of yummy nut-covered fudge balls that I have eaten around Christmastime.