Answer: Ciliocytophthoria (a.k.a. detached ciliary tufts)
This case is interesting in that detached ciliary tufts (DCTs) are uncommonly seen in stool specimens, and therefore I think that their presence threw a few people off. DCTs are formed when ciliated epithelial cells are damaged and the ciliary plate becomes detached from the rest of the cell. They are commonly seen in specimens from the lower respiratory tract (especially in patients with asthma and other inflammatory conditions), and can also be seen in various body fluids when ciliary epithelial cells may be present (e.g. peritoneal fluid with ciliary metaplasia).
DCTs can be identified by their small size (15-20 micrometers in diameter) and lack of nuclear features. They are occasionally confused with trophozoites of the ciliated parasite, Balantidium coli, but are easily distinguished by their significantly smaller size and lack of a kidney bean shaped macronucleus. Although I didn't give you the size of the DCTs (arrow), you can estimate their size based on size of the background bacteria (arrow head).
Thanks again to Miranda from my sister-lab for donating this case!