I found my first Vorticella and then this effect by accident, my thumb partially covered the light source while reaching for the stage x, y knobs. Then I remembered a thread I read here about making shaped diffusers to get a similar effect. I eventually just cut a V notch out of a post-it note and laid it over the bottom light source. As usual, it looked much better through the oculars than I seem to be able to photograph.
Here is
a video of him and some other critters in the water.
This is the Vorticella with 10x objective, using Oblique Illumination lighting to highlight the internals of the Vorticelli.
Here he is at 40x...
And another...
