Relatively long non-motile filaments (200-300 µm). Bent and irregularly coiled filaments with incidental true branching. Cell septa are clear with indentations. Cells are large and spherical, or oval shaped (1.6-2.0 µm). Filaments are found within the floc structure. The filament staining is variable, although it is usually Gram positive and Neisser positive. Usually easy to identify due to its Neisser staining properties. Stains entirely purple and looks like poppet beads. There is no sheath and there are no sulfur granules. Poly-ß-hydroxybutric acid (PHB) granules are frequently observed as dark intracellular granules. Attached growth is usually uncommon.

Three subtypes are known.

This filament is usually found in environments where there is low DO or low F/M and the presence of organic wastes. Wastes containing starch seem more selective to this filament. Bulking is more common in industrial wastes. The filament appears to be facultative fermentative, which is unique for most filaments.

Manipulation of F/M (usually an increase) and DO concentration can be used to control the filaments. A selector may be used and chlorination. System changes include changing from a complete mix to plug flow aeration basin configuration.

N. limicola ranks 12th in number of predominance. Typically not found in kraft mills.