Labyrinthuloides (lab-ee-rin-thule-oid-ees). Labyrinthuloides is a thraustochytrid - very closely related to the labyrinthulids. The trophic form is a usually a large mass of cytoplasm giving rise to a system of fine rhizoid-like ecotoplasmic extensions. This image is from a culture growing on agar showing cells and some of the ectoplasmic strands. Phase contrast.