Borg ship.
Huge cube-shaped spacecraft. One face of the cube is five kilometers square. First encountered by the Enterprise-D near System J-25 in 2365. It had a highly decentralized design and Enterprise-D personnel reported finding no specific bridge, engineering, or living areas. Combat experience showed the ship to be equipped with powerful energy weapons and capable of repairing major damage almost immediately, including the impact of direct phaser hits.
A borg vessel of a totally different design was used in the borg incursion of 2369, in which a transwarp conduit was used to reach the Alpha Quadrant much more rapidly than was possible with normal warp travel.