we found Eutreptiella gymnastica, the dancer.
With its two unequal flagella that after a while on the slide I can not see them anymore. Loses them?.
100X immersion objective
Oblique polarized light and phase contrast
Panasonic GH4 camera
Video link:
https://www.youtube.com/watch?v=qYBLsWxOtjY
Video frame ONLY for preview:

Regards
carlos