 SCP-752 is an underground city in the northern mountains, spanning kilometers squared, population approximately 10,000. An array of electric lighting devices powered by a geothermal generator create day and night matching the rhythm of the outside world. A shield, built of an unknown metal, surrounds the entire city and blocks all known signals and radiation, including sonar. Study of this metal is restricted to on-site efforts to minimize the chances of containment breach. SCP-752-1 are the inhabitants of SCP-752. Physically, SCP-752-1 appear human. However, the social behavior exhibited by SCP-752-1 in large groups bears no resemblance to that of humans or any other social mammal.