Fluorescent-stained Spirochaeta americana. The red spiral-shaped figures are dead cells; green ones are living.

Fluorescent-stained Spirochaeta americana. The red spiral-shaped figures are dead cells; green ones are living.
Photographer: Richard B. Hoover, Elena Pikuta and Asim Bej, NASA/NSSTC Univ. of Alabama at Huntsville and Univ. of Alabama at Birmingham