This order includes some of the most primitive of all known insects; approximately 370 species have been named. Some species are accidental invaders of homes, commonly known as silverfish or firebrats.

Here's what silverfish look like.

Most species live in the soil, in rotting wood, or in decaying leaves in forests. Characteristic form is a smooth tapering insect with the body covered with glistening scales; a pair of long antennae and three long slender structures at the tip of the abdomen.