Protists both and multicellular that possess two different types of flagella during their motile .

Included among the stramenopiles are the brown algae ( or ), golden algae ( or ), diatoms ( or ), and ( or ).

The chloroplasts of the stromanopile posses four membranes versus the two of cyanobacteria, that is, the inner membrane and the outer membrane. The possession of these four membranes by these chloroplasts may or may not imply secondary endosymbiosis and potentially even .

If a case of secondary endosymbios (or higher), then it is likely that the chloroplasts represented captured red algae.