Is it possible that they are all bacterium? Both the samples I found these in were older samples. The one new sample I had I found nothing but bug parts.
Bacteria can only be seen under 1000x mag and oil immersion. Those are way too big (like take over the world single handedly big!) for bacteria and don't look right for bacteria due to the shell around them. They don't look like coccidia or tapeworm eggs. I'm going with nematode eggs.