A beautiful, artistically coloured image of magnetite nanoparticles (~10 nm in diameter). It takes 20,000 of these particles in a row to span the width of a human hair.
Magnetite nanoparticles imaged using High-Angle Annular Dark-Field - Scanning Transmission Microscopy.
The image was blended with artificially generated colours on GIMP.
More about the image and magnetite nanoparticles here: