Protozoa are natural predators of bacteria. but some bacteria can evade digestion once phagocytosed. Some of these resistant bacteria can be packaged in the fecal pellets produced by protozoa. protecting them from physical stresses and biocides. https://www.spidertattooz.com/OPI-GelColor-The-Color-That-Keeps-On-Giving-0-5-oz-HPJ07-p22791/