Zeiss IM35 microscope.
X10 phase long focus objective.
Bright field and phase photos.
Optical setting x1.0x.
Pictures taken with hand held Samsung S7 phone at ocular due to my laptop being busy elsewhere!
My daughter and I think this is Vorticella.
I think this Vorticella as bottom of cell appears to have curled up flagellum at bottom. See below from Patterson, Free living freshwater protozoa: