Pelomyxa palustris is usually reported as a large multinucleate amoeboid pelobiont, 100-5000 microns long, with small non-motile flagella, endosymbiotic bacteria, refringent cytoplasmic granules (sand and food particles); movement takes place usually as a monopodial progression, with a central forward flow of cytoplasm along a single axis, and the cytoplasm spills outwards at the anterior-most tip of the flagellum. The posterior uroid is involved in the capture of food which is comprised of detritus and algae. The cysts are about 100 microns in diameter. This species has been reported from freshwater and soils. This species has many inactive flagella attached to single basal bodies. Cones of microtubules arise from the bases and sides of the basal bodies; sometimes enclosing a nucleus. The nuclei may also be surrounded by endosymbiotic bacteria instead of microtubules. The axonemes of the flagella may or may not have the standard 9+2 arrangement of microtubules.