en Altadefinizione. The one-celled long and slender diatom, up close: discovered in 1703 with the invention of the microscope. We observe them magnified 10,000 times: water expelled through the skeleton, mucilage constantly emitted, allowing it to glide. Their energy comes from sunlight. They divide and disperse. The narrator, conversing with a young woman, says their remains cover one-third of the earth's surface. They have uses in petroleum, explosives, and polish. Some live in isolation, some in colonies, like elaborate fans. They can move in clusters. Many small animals eat them. We watch them slide on each other in long strings.