Borg sphere

The Borg sphere was a type of huge sphere-shaped starship used by the Borg Collective.

History
In 2368, one Borg sphere was part of the fleet of the Borg-Cyberman Alliance along with Borg cubes and Cyber-ships of the Cyber-Armada. It was present at Delta IV in the Delta system, where the alliance overran the member planet of the United Federation of Planets. The fleet was found by the Starfleet vessel USS Enterprise (NCC-1701-D), which was immediately attacked and forced to retreat into the Paertes Nebula. The fleet then proceeded to Cogen V where, in the midst of assimilating the planet, the Cyber-Armada broke off from and overwhelmed the Borg forces. Soon after, the wreckage of many Borg vessels was found by the Enterprise, with Lieutenant Data determining that the majority of the Borg ships previously seen at Delta IV had been destroyed by the Cybermen. (COMIC: Assimilation²)

Behind the scenes
The Borg sphere is, after the Borg cube, the most common type of Borg ship to be seen in Star Trek, having appeared in the movie ' and various times in the spin-off series '. In-universe, their appearance in Assimilation² takes place years before their on-screen appearances. In First Contact, the Borg sphere demonstrates the ability to time travel, fulfilling the ambition that the Borg make at the end of Assimilation².