I was so sorry to interrupt this tiny roundworm his (or hers?) feast on the spores of the smut fungus Parvulago marina which had infested my culture of Eleocharis parvula. However, a dose of Lactophenol Cotton Blue was more than it could stomach so it just went belly up and died. Oops.
400X under the microscope. I later found this smut fungus hadn't been collected in Norway since the late 1800's. About time, I'd say.