A childhood belief about general

When I was little I learned about micro-organisms, and how they were tiny invisible creatures that were all around us. So when my friend was sleeping over, she thought she heard a voice, and we became convinced the micro-organisms were talking to her! I had read a book that said you could fit a certain number of them on a head of a pin, just to demonstrate how small they are. But we took this to mean that they lived on pins, so we spent a long time staring at a head of a "pin" (it was actually a thumb-tack) and trying to contact the micro-organisms! We were strange kids.