Bolidophyceae is a class of photosynthetic heterokont picophytoplankton, and consist of less than 20 known species.

[1][2][3] They are distinguished by the angle of flagellar insertion and swimming patterns as well as recent molecular analyses.

[4] Bolidophyceae is the sister taxon to the diatoms (Bacillariophyceae).

They lack the characteristic theca of the diatoms,[5] and have been proposed as an intermediate group between the diatoms and all other heterokonts.

[4][6] In the gallery, all scale bar represent 1 μm.