[1] They are characterized by a propensity to move through gliding on their posterior cilium or through filopodia,[2] a lack of scales or external theca, a soft cell surface without obvious cortical filamentous or membranous skeleton, two cilia without scales or hairs, tubular mitochondrial cristae, near-spherical extrusomes, and a microbody (probably a peroxisome) attached to the nucleus.

[3] In 1993 Cavalier-Smith described the sarcomonads as a subclass known as “Sarcomonadia”, an assemblage of unrelated cercozoans (thaumatomonads, proteomyxids, cercomonads...) and excavates (jakobids), in the now defunct class “Heteromitea”, in the old phylum “Opalozoa”.

This subclass was created to lump together protozoa that have an anisokont type of zoospore (i.e. two cilia of different lengths), are non-thecate and have isodiametric extrusomes.

[2] Sarcomonadia was composed of three superorders: Phylogenetic analyses published in 1997 showed close relationships between filose and reticulose amoebae and zooflagellates such as the sarcomonads, and they were grouped under the provisional phylum Rhizopoda.

[5] Later, in Cavalier-Smith's A revised six-kingdom system of life of 1998, the phylum Cercozoa was created to formally establish this group of protists previously known as Rhizopoda.