The image shows the siliceous skeletons of diatoms (tiny planktonic organisms) preserved in lake sediment, Lake Toskaljarvi, Finland. The sample was collected as part of a study of the variation in sedimentation of Arctic lakes and past climate change. Diatoms from Lake Toskaljarvi, Finland The image represents an area approximately 70 µm wide. Sample courtesy of Prof. Roy Thompson and Shirley Derrick, Geology and Geophysics, University of Edinburgh. This article was published on 2024-07-01