A Borg sphere being ejected from a Borg cube during the attack on Earth in 2373
The Borg Queen's sphere was a Borg sphere attached to a Borg cube that was used by the Borg when they tried to assimilate Earth in 2373.
After the attacking Borg cube was destroyed using Captain Jean-Luc Picards knowledge from his time as Locutus. This sphere left the cube before it was destroyed, and traveled back to the year 2063, in order to prevent the First Contact. It was destroyed by the USS Enterprise-E, which had followed the Borg through the temporal vortex. (Star Trek: First Contact)
The remains of the sphere were later found by a group of scientists in the Arctic Circle in 2153, buried under snow and ice of a glacier. Two drones had survived the crash and were preserved in the ice. Upon regeneration, the Borg drones assimilated the scientists and collected all remains of the sphere to include it to the assimilated transport Arctic One. This transport was later destroyed by Enterprise NX-01. (ENT: "Regeneration")
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