<unk>  or<unk>  refers to the black, "tarry" feces that are associated with gastrointestinal hemorrhage. The black color is caused by oxidation of the iron in hemoglobin during its passage through the ileum and colon.
Melena
Choana
PolyHeme
Heliox
Seafood
Essiac
Monkeypox
Chigger