An ARMAN cell (center, orange) is penetrated by a needle-like protrusion from Thermoplasma (lower left), an Archaea that lives in the same acidic pools as ARMAN. The much smaller, yellow lozenges are viruses that also infect ARMAN cells. A probably dying ARMAN cell (top) has grown to a diameter of about 1,000 nanometers - less than one hundredth the width of a human hair. Credit: Luis Comolli/LBNL