Silverfish head. Coloured scanning electron micrograph (SEM) of the head of a silverfish (Lepisma saccharina). This primitive insect has remained unchanged for millions of years, and is considered a living fossil. The head is covered in sensory hairs. Its mouth parts are across bottom. The compound eyes (green) are either side of the head, and two antennae protrude from its head at far left and right. The silverfish, so named because it is covered in tiny shiny scales, is a common household pest.