Atoms
Figure 1 : A photograph of about 500 atoms of Niobium (41) and Selenium (34) neatly arranged at the surface of a crystal (darker atoms are simply lying lower in the surface). The image was taken using a special kind of microscope (called a scanning tunneling microscope) by Professor Nai-Chang Yeh of Cal Tech's Condensed Matter Physics Group. Despite what you may have previously thought, it IS possible to "see" atoms.