The smallest life-form on Earth
This cryo-electron tomography image reveals the internal structure of an ultra-small bacteria cell like never before. The cell has a very dense interior compartment and a complex cell wall. The darker spots at each end of the cell are most likely ribosomes. The image was obtained from a 3-D reconstruction. The scale bar is 100 nanometers.

Diverse uncultivated ultra-small bacterial cells in groundwater
by Luis R. Comolli, Jillian F. Banfield et al.
Nature Communications 6, No. 6372, 27 February 2015
doi:10.1038/ncomms7372