Nucleogenic Lifeforms
Nucleogenic lifeforms are intelligent beings from another dimension, who are able to enter this space-time continuum through interspatial fissures but are only able to survive for a few seconds. The Ankari of the Delta Quadrant are able to communicate with them, and view them as "spirits of good fortune".
In the 2370s, the Ankari provided assistance to the heavily-damaged USS Equinox, a Federation starship brought to the Delta Quadrant by the Caretaker. They summoned one of the lifeforms to bless the Equinox's journey. Intrigued by the fact that the being emitted high levels of antimatter, the Equinox crew obtained their own summoning beacon to study them and designed a containment field to keep the lifeform from leaving, not knowing that they were condemning it to death. The lifeform they summoned died before they could deactivate the field.
Examining the remains, the Equinox crew found that the being's cellular structure contained high levels of nucleogenic energy. The energy from one lifeform was enough to increase their warp factor by .03% for a month, and by killing more lifeforms the Equinox was able to travel ten thousand light years in less than two weeks. At the time the Equinox encountered Voyager, it would have taken 63 more lifeforms for them to return to the Alpha Quadrant. The lifeforms retaliated by attacking the Equinox, weakening its shields by opening interspatial fissures in close proximity. Whenever the shields failed, the lifeforms entered the ship and induced lethal thermolytic reactions in crew members' bodies through touch.
By 2375, the Equinox was nearly disabled by the lifeforms' attacks and would have succumbed, were it not for the USS Voyager's timely intervention. Personnel from both ships cooperatively developed an auto-initiating security grid that would trap the lifeforms whenever they appeared. After the Equinox crew's actions were discovered, they broke out of confinement and stole the field generator for the security grid. This staved off further attacks, though Captain Rudolph Ransom began to have second thoughts about killing the lifeforms. He was ultimately relieved of command by his executive officer, Maxwell Burke.
Meanwhile, the lifeforms continued to besiege Voyager. As they were unable to capture the Equinox or develop a translation matrix for the lifeforms' language, Commander Chakotay suggested that they seek out the Ankari as intermediaries. Through them, Captain Kathryn Janeway promised the lifeforms that she would allow them to destroy the Equinox if they halted their attacks. When Voyager caught up with the Equinox, Ransom beamed most of his crew onto Voyager and dropped the Equinox's shields. The lifeforms invaded the ship, killing the remaining crew and attacking the warp core. They withdrew back to their native realm after the Equinox was destroyed. (VOY: "Equinox", "Equinox, Part II")
