An interesting fact I picked up the other day, just in case you wondered why your shit is typically brown:

The brown colour of feces is due to the action of bacteria on bilirubin, which is the end product of the breakdown of hemoglobin (red blood cells)

Bilirubin is a useless and toxic breakdown product of hemoglobin, which also means that it is generated in large quantities. In the time it takes you to read this sentence aloud, roughly 20 million of your red blood cells have died and roughly 5 quintillion (5 x 1015) molecules of hemoglobin are in need of disposal.

In the liver cells (hepatocytes) the bound bilirubin reacts with glucuronic acid to form conjugated bilirubin. Most of the conjugated bilirubin is secreted into the small intestine with the bile. In the large bowel, bacteria convert bilirubin into the yellow-brown pigment (urobilinogen) that gives feces its characteristic color. Some of this pigment re-enters the blood from the colon and is removed by the kidney into the urine (characteristic color).