Then, another member there identified it as possibly an Entamoeba coli cyst. Not that I would know, but it seems incredibly active for a cyst, actually producing contractile vacuoles, just like a paramecium.
I do have a personal interest in these though, as I once contracted amoebic dysentary and promply lost 44 pounds in 30 days. I still think this would be a wonderful quick diet plan for the morbidly obese, if done under close supervision.

Here's the video of it, recorded with a Nikon 40x Plan Achromat.