Anything fecal has to do with feces: what children call "number two." In other words, fecal matters involve poop.
A successful children's book is called "Everyone Poops." That's a book with some seriously fecal subject matter. All fecal issues have something to do with feces: what people commonly refer to as poop or crap. You will get fecal material on your shoe if you step in dog poop. A veterinarian may run fecal tests to see if your pet has a disease. The fecal matter of an elephant is enormous.