Shoot Skulls to Spawn a Zursa
This easter egg can be helpful to complete the main quest a bit earlier by spawning in a Zursa before round 16.
At the cosmodrome POI, there are three skulls that need to be shot with the Necrofluid Gauntlet wonder weapon. These skulls do not have to be shot in any order. Shooting one will cause its eyes to glow and shooting all three will make the Zursa spawn.
The bear will always spawn from the same location.