My backyard bird bath is not usually the place where I look for interesting critters, as it fills automatically every day with chlorinated tap water, has no plants, and is a generally less-than-hospitable place for pond life.  However, a sample during cleanout of its green and unlovely, algae-coated interior revealed this video of a bedelloid rotifer chowing down on a typical rotifer diet, namely, almost anything that comes along, be it green, dead, or wriggly: