Fifteen years ago I was in my final year of my biology degree and I was investigating the cow rumen cilliates using the TEM. Small spherical bodies were found in some of them which couldnt be describes. They weere not part of the anatomy of these paramecium nor were they bacteria. However they seemed to go through a life cycle where they changed from being granular to dense. The cilliates affected by their presence lokked moribun. I never did get to find out what they were and I would be most interested to see if any researcher discoved anymore than I did. Ive surfed the net and cant find anything like the photos I acqured of these mysterious bodies.