Black Moon

The Black Moon is the "egg" of Lilith, a transport vessel created by the First Ancestral Race to send Lilith to Earth. It collided violently into Earth 4 billion years ago in the event dubbed "First Impact", and came to rest deep beneath the Earth's surface in the region that would eventually become Hakone, Japan. Buried under the surface, the Black Moon formed a spherical underground cavity of gigantic size termed a "GeoFront", around which Tokyo-3 and NERV Headquarters were eventually built. According to production sketches, the Black Moon is 13.75 km in diameter.

In Episode 26', the Black Moon emerged out of the ground and into Earth's atmosphere where Lilith collected all the souls of mankind into it for the purpose of Instrumentality. Later, after Instrumentality was halted, the Black Moon exploded, releasing all of the souls held within it.

Rebuild of Evangelion
The Black Moon appears in Evangelion 3.0: You Can (Not) Redo, emerging from the ground during the awakening of Evangelion 13. It has been heavily modified into a shape resembling a. After the impact caused by Evangelion 13 is stopped, the Black Moon fails to completely rise out of the ground, and remains visible as a large spherical 'hill'.

In Evangelion: 3.0+1.0 Thrice Upon A Time, NERV HQ transported the Black Moon to the epicenter of the Second Impact, (the South Pole) to be used as raw material for the NHS Ships to create new spears. These new spears reopened the Gates of Guf, allowing for Evangelion 13 to travel to the Anti-Universe and begin the Fourth Impact.