I can think of two things that got me hooked on the wonder and awesomeness of biology. One was 'discovering' my brother's microscope. It's a single eyepiece light microscope. I still have the beast and it still works, although it needs a new bulb. Once this device was discovered, it opened a whole new world to me: pondscum. That was when I was first introduced to a beautiful little beast. I didn't know its name or even what the hell I was looking at. What I did know is that it was love at first sight. Now I admit our relationship faltered when I met colecovision and was ruined when I realized the opposite sex was more than just a cootie factory. However, it ignited a longing that burned deep within me, forever influencing my...well let's not get overly dramatic.
The shear awesomeness that comes from seeing these little beasts swimming around in the pond behind your house with your own eyes, well eye since it was a monocular scope is inspiring. Here's a video using a much better scope than I had, which I hope can give you an inkling into that sense of wonder that arose in a child.
There are many aspects of Paramecium biology worthy of discussion: separation of 'somatic' and 'germ line' nuclei, the trichocyst, digestive progression, whole genome duplications, macronuclear development, RNA editing, endosymbiosis, etc. We will touch on a few of these in the next few weeks.