Armadillidiidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of woodlice

Woodlouse

A woodlouse is a crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs...

, a terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 group in the order Isopoda

Isopoda

Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots and...

. Unlike members of other woodlouse families, members of this family can roll into a ball, an ability they share with the outwardly similar but unrelated pill millipede

Pill millipede

Pill millipedes make up two orders of millipedes, often grouped together into a single superorder, Oniscomorpha. The name Oniscomorpha refers to the resemblance of pill millipedes to certain woodlice, namely the pillbugs of the family Armadillidiidae, also called "potato bugs", "doodlebugs", or...

s and other animals. It is this ability which gives woodlice in this family their common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 of pill bugs, roly polies or potato bugs. The best known species in the family is Armadillidium vulgare

Armadillidium vulgare

Armadillidium vulgare, the pill-bug or pill woodlouse, is a widespread European species of woodlouse. It is the most extensively investigated terrestrial isopod species.-Description:...

, the common pill bug.
Woodlice in the family Armadillidiidae are able to form their bodies into a ball shape, in a process known as conglobation.