Polwocz

Polwocz were creatures native to the Spinward sector. They laid their eggs underground, where they lay dormant for as long as decades. When they finally hatched, the larvae were rumored to have eaten entire cities. Imperial Intelligence referred to a deep-cover Infiltration agent intended to stay in place for years before breaking cover in one devastating blow as a "polwocz."

Text and facts from the “Polwocz” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.