Much of the material that passes from the liver is not stones--it is bilary sludge. It is clear that it comes from the liver because it has a liver smell, and is accompanied by cholesterol stones. A handfull of stones in the liver probably won't cause any symptoms, but if the liver becomes packed with stones, sludge, and old clumps of matter that defies description, a chronic debilitating illness results.
Matter can also come from the intestinal tract. Old feces and new feces have a distinctly different appearance. Some of it takes the form of intestinal plaque, which looks like a wad of Seran wrap, except thicker. It floats. Old feces often becomes encapsulated in plaque.
I have the advantage of having had the personal experience of passing about five gallons of this material over a three month period and inspecting it and photographing it closely.