Cells of rigifilids are covered with either a single or a double-layered submembrane pellicular lamina that makes them rigid in consistence. Slender branching
filopodia emanate from a ventral aperture of the
cell and are employed to collect
bacteria upon which they feed and to attach the organism to the substratum. Around this aperture, the pellicle is reflexed around forming a peristomial collar.
Other notable features are flat and irregular shaped
mitocondrial cristae, a single dorsal
nucleus and the lack of
centrioles and
cilia.[2]
^Cavalier-Smith, Thomas (2013). "Early evolution of eukaryote feeding modes, cell structural diversity, and classification of the protozoan phyla Loukozoa, Sulcozoa, and Choanozoa". European Journal of Protistology. 49 (2): 115–178.
doi:
10.1016/j.ejop.2012.06.001.
PMID23085100.
^Yabuki A, Ishida KI, Cavalier-Smith T (2013). "Rigifila ramosa n. gen., n. sp., a Filose Apusozoan with a Distinctive Pellicle, is Related to Micronuclearia". Protist. 164 (1): 75–88.
doi:
10.1016/j.protis.2012.04.005.