U.S. Air Force Staff Sgt. Randal L. Marks, 86th Medical Support Squadron chemistry and shipping noncommissioned officer in charge, prepares a blood sample to examine under a microscope at Ramstein Air Base, Germany, June 8, 2020. Marks was specifically looking for rouleaux in the blood sample, which is when red blood cells are stacked on top of each other. (U.S. Air Force photo by Airman 1st Class John R. Wright)