Pill bugs (AKA rollie pollies, doodle bugs, or wood shrimp) are actually crustaceans, not insects. They have the distinguishable trait of defensively rolling up into a tight ball when they are disturbed. Researchers have found that they also have the unique ability to consume heavy metals like copper, zinc, lead and cadmium and crystallize them in their bodies. Having this special capability makes them important as a natural clean-up for soil pollutants, as they can survive in contaminated sites where other creatures cannot. Pill bugs reestablish healthy soil and prevent toxic metal ions from contaminating groundwater.