The energy focusing ship was an organic ship utilized by Species 8472. Larger than its bio-ship counterpart, the vessel was used to focus energy from other bio-ships to form an extremely powerful directed energy weapon. This was completely with the assistance of eight bio-ships that would form a ring around the energy-focusing ship and fire on it. The energy-focusing ship amplified and focused the energy bolts of the eight bio-ships into one huge bolt. This energy beam was capable of destroying whole planets.
An energy focusing ship was used to destroy a Borg planet in 2374, with assistance from eight other bio-ships. (VOY: "Scorpion") Using this weapon, Species 8472 systematically annihilated planet after planet in Borg space. In a battle that occurred in the region of Borg space which the Borg designated Matrix 010, Grid 19, eight planets fell to it. (VOY: "Scorpion, Part II")
Background information Edit
The manner in which this style of ship fires – multiple beams of energy converging into one large beam – bears a striking resemblance to that of another sci-fi planet-killer, the Death Star from the Star Wars films. Upon creating the powerful beams for Star Trek: Voyager, however, Visual Effects Supervisor Ronald B. Moore was interested in doing something slightly different than the Death Star, finding the solution of the vessels converging and then cumulatively focusing their firepower to be "more interesting." (Cinefantastique, Vol. 29, No. 6/7, p. 95)
While Steve Burg was designing the Species 8472 bio-ships, the producers notified him about the scenes demonstrating swarms of the ships. As a result, the bio-ships had to look good in formation. (Star Trek: The Official Starships Collection issue 43, p. 12)
After he and Visual Effects Coordinator Cheryl Gluckstern devised the converged beams, they were animated by Greg Rainoff at Digital Magic, via Harry animation. (Cinefantastique, Vol. 29, No. 6/7, p. 95)
This type of vessel is described as a "frigate" in Star Trek: Armada II, wherein it can use its energy focusing ability while grouped with anywhere from four to eight other ships.