Assorted diatoms as seen through a microscope. These specimens were living between crystals of annual sea ice in McMurdo Sound, Antarctica. The tiny phytoplankton are encased within a silicate cell wall (image digitized from original 35mm Ektachrome slide; image by Gordon T. Taylor, Stony Brook University (USA) and provided by the U.S. National Oceanic and Atmospheric Administration Corps Collection; retrieved via Wikimedia Commons; the image was modified by MIC). The cover is published under the Creative Commons Attribution (CC BY) license.