Answer: Hymenolepis nana eggs
Most people who wrote in with the answer to this were correct - these are good examples of the thin-walled H. nana eggs, with a central 6-hooked embryo, and 4 to 8 polar filaments radiating from thickenings of the envelope surrounding the embyro (onchosphere). The eggs measure between 30 to 50 microns in diameter.
H. nana, also known as the dwarf tapeworm, most commonly infects children, and is acquired through ingestion of eggs, or infected beetles (the intermediate host). The usual definitive host is a rodent.