A "armoured" and flagellated algae
In this video we look two of them,
one with the usual form
but the other is beginning to divide?
or is another Trachelomonas specie?
Oblique polarized light.
40X objective.
Panasonic GH4 camera
Video link:
https://www.youtube.com/watch?v=LyF05Oko8tY
Video frames preview:

Habitual form

Beginning to divide?
Regards
carlos