Silverfish (Lepisma saccharina). Coloured scanning electron micrograph (SEM) of a silverfish. The silverfish is a primitive insect that has remained unchanged for millions of years, and is considered a living fossil. The silverfish is so named because it is covered in tiny shiny scales. It is a common household pest, feeding on starches in food, books and clothes. Magnification x60 when printed 10 cm wide