Description of Spongomonads:
Circumscription: Heterotrophic flagellates, two flagella inserting at the apex of cells, which are embedded in a matrix of iron-rich mucoid globules, some forming large colonies. Ultrastructural identity: Mitochondria with tubular cristae. With two flagella inserting in near parallel basal bodies, basal bodies with radiating fibrous anchorage structures and radiating microtubules, as well as cross-striated fibres running between and away from the basal bodies. Dictyosome located adjacent to nucleus and basal bodies. Synapomorphy: Tubulocristate flagellates embedded in globular mucoid iron-rich matrix.