<em>Comatricha filamentosa</em> is a myxomycete belonging to the genus <em>Comatricha</em>, order Stemonitidales, class Myxomycetes. The species is distinguished within the genus by features of its filamentous capillitial threads and spore morphology, which are used as diagnostic characters in taxonomic identification. It has been recorded from Europe, where it inhabits decaying wood and plant litter in forest and woodland habitats. Like other plasmodial slime molds, <em>C. filamentosa</em> passes through a motile plasmodial feeding stage, consuming bacteria, fungi, and decomposing organic matter, before forming fruiting bodies under conditions of environmental stress or nutritional depletion. The resulting sporangia release spores suited for wind dispersal. This species plays a role in nutrient cycling within woodland ecosystems. No quantitative biological metrics are available, and it has not been assessed by the IUCN.