Critters that feed on things leave leavings, feces and other things. This was true of dinosaurs, and is true of people and other animals. Even viruses leave their "scat" behind, as do molds. See numbers 6, 7, and 8.

Britannica.com says, "No specialized elimination mechanisms are present in algae, fungi, protozoans, and slime molds, the main groups of protists. Metabolic wastes (carbon dioxide, water, oxygen, and nitrogenous compounds) diffuse through the cell membranes of these unicellular organisms into the outside environment. Particulate wastes pass from the bodies of certain protozoans to the exterior by way of small openings in the body surface—anal pores and other cell openings. Elimination in protists is carried out passively and therefore requires little or no expenditure of metabolic energy on the part of the organism."

So, where's the poop? Are black holes just universal flush mechanisms?