Trouble is, they were fast moving and I was attempting to use darkfield, without any flash.
Now, I know my optics are mediocre and my setup is not really adequate for the job, but I was not anticipating this picture:
(This is a heavily cropped version of a smallish colony - this picture was taken with a 20X objective.)
I find it an interesting picture, but not very good. I also don't entirely get how the colony wound up looking like that.
As an aside, we're having unseasonably warm weather here in the Chicagoland area, and I wonder if that's going to affect the Volvox population. I only typically see Volvox in March and April, but with 70 degree weather all this week, this might be the only time I see them in numbers.