The best known species in the family is the common pill bug. These arthropods eat paper and roll into balls just to waste their time. Moisture is essential to pill bugs due to their breathing organs, which are like gills. Pill bugs, although often thriving in damp areas, have often been known to live under rocks, where they can easily get squished. Pill bugs' entertaining posture is curling up into a ball. Pill bugs have no specialized predators, though they try to kill flies, but fail. They are known to be caught in spider-wider webs. Pill bugs don't even know one word you say. They just say stuff like "You fired!" (of whose meaning they have no idea).