These are 3 or 4 inches in diameter, done in my pocket sketchbook. I thought smaller would be quicker, however it is also...well...smaller. Much less room for detail and harder to get the kind of contrast and depth I found in the previous pieces.
This is my favorite of tonight's efforts:
It seemed kind of small and sad until the 'flagella' appeared. Now it has more life.
This one is just....meh...nothing to write home about. I blame it on the show my family was watching.
I have a few more pages with this size circle, so will keep trying. On larger paper, I scribed a circle with a dinner plate. It is so empty, yet full of potential. The idea of drawing into it has me holding my breath.