The Raven Surveillance Units are a veritable swarm of small, semi-intelligent robots, connected by a hive mind network. They were released into the Facility by Archibald, who uses them as his personal spy network. Before this, they were apparently a common sight in the streets of Archibald's simulations
Ravens are small, playful robots that take great joy in recording, photographing or otherwise collecting information on a great variety of subjects. They propel themselves though the air using two miniature jet engines hidden in the half-shells displayed behind their body like wings. When threatened, they'll retreat into their shells and roll away.