The Winogradsky column, invented by Sergei Winogradsky, is a device for culturing a large diversity of microorganisms. Pond mud and water are mixed into a column using carbon sources like newspapers and sulfur sources like egg yolks. Left in the sun for a few months, the column becomes a colony rich with microorganisms, bacteria, cyanobacteria, and algae. In this video, scientist Karen Dodson shows you how to make your own.