The Silicoflagellates (= Dictyochales) are a very small group with few species. During one stage of their live they have flagella.
Obj. 40x, DIC, crop, seawater plankton.
The middle axis was 65 µm long.
Again I have never seen a live one of these, though I have seen plenty of their silica skeletons in dredgings and fossil marine deposits. Very nice to see, thank you.