Is a pill bug a.k.a. a rolly polly a crustacean?

Yes the pill bug is a crustacean. Crustaceans are a large group of about 10,000 animals. They include sandhoppers, woodlice, waterfleas, barnacles, crayfish, shrimps, prawns, crabs and lobsters. They all have large, jointed bodies and jointed legs. They are invertebrates so they don't have a backbone. Most crustaceans have shells around their bodies, this keeps their soft body safe. Many have a set of claws, or pincers, on their front legs. They use these to defend themselves and grab their prey. Crustaceans begin life as eggs, these hatch into tiny larvae which make up much of the floating plankton which other sea animals eat. As each larvae grows, it sheds its shell and grows a new one which is bigger. This is called moulting. When the larva becomes an adult, it continues to grow and moult. The best known crustaceans are the large shellfish. Yes, a pill bug or rolly polly (Porcellia scaber, being perhaps the most common), belongs to the Sub-phylum, crustacea.