What’s smaller than a bacterium? The virus that infects it, of course. This image (at 30,000 X) is from the new eBay transmission electron microscope. The balloonish thing is a bacterium (perhaps Limnohabitans curvus) from Lake Matoaka. The little dots highlighted by the arrow are the heads of phage viruses assembling in the body of the bacterium. The phage heads are 50 nanometers across. (A human hair is around 40,000 nanometers in diameter.)