[1] They were initially thought to be loricate choanoflagellates[2] but were shown to be a separate phyla entirely upon the discovery of chloroplasts, placing it among the photosynthetic stramenopiles.

The bolidophyte form lacks silica plates and has two unequal flagella inserted ventrally, vaguely reminiscent of Chlamydomonas.

Unlike the diatoms, the Parmales are able to grow in silica-limiting environments because the synthesis of the silica plates is not directly connected to growth or reproduction.

[4] The Parmales actively feed on nanophytoplankton such as Prochlorococcus and Synechococcus and are one of the most important grazers on these cyanobacteria in oligotrophic waters.

[7][8] Within the water column, Parmales are found in the upper, euphotic portion where they remain without difficulty due to their small size.