The Metroids

The Metroids are a species of intelligent predators that formed their own organized movement on their homeworld of SR388 against the X-Parasite, which the Chozo government created the Metroids to eat. Despite their primitive nature, the Metroids usually stuck together in small tribes while hunting for X-Parasites, though it was because of this that various factions in the galaxy, most notably the Space Pirates, were able to capture large amounts of Metroids for experimentation and sometimes forced servitude.