When I first saw one of these the other day in a freshwater sample, I had a bad angle, and it appeared to behave like a rotifer. However, a contractile vacuole could be seen which indicated ciliate, not rotifer. After preparing a few more slides, I was able to locate a pair of them close enough to the cover slip that I could focus with my 40x oil objective. The new angle revealed that the organisms were inside a lorica, and based on the lengthwise attachment of the lorica to the algae, the shape and length of the organism, and the fact that it angled up when emerging from the lorica, it appears this is Platycola. Very cool find! Shot with 40x oil objective, Nikon D750 at 1.0 and 1.5x sensor crop, and Nikon inverted diaphot.
Platycola inside its lorica
Re: Platycola inside its lorica
Very nice video and good ID !