This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
The Silver Blood homeworld was a deuterium-rich Class Y planetoid located in the Vaskan sector of the Delta Quadrant. It was the homeworld of a biomimetic lifeform known as the "Silver Blood". (VOY: "Demon")
Prior to 2374, the Silver Blood was a non-sentient liquid that coated parts of the planetoid. In that year, USS Voyager approached the planetoid to mine its deuterium and replenish its energy reserves. A shuttle carrying Lieutenant Tom Paris and Ensign Harry Kim landed on the surface and inadvertently made contact with the Silver Blood, imparting sentience and intelligence and causing it to duplicate them.
Following first contact, a deal was struck: in return for being allowed to refill their deuterium supply, Voyager allowed the Silver Blood to duplicate their entire crew, after which Voyager left the planetoid. (VOY: "Demon")
By the following year, the Silver Blood had duplicated Voyager itself. The crew developed an enhanced warp drive that would allow them to return to Earth in just over two years, but the drive caused the Silver Blood to loose molecular cohesion. The Silver Blood attempted to return to their homeworld, but were destroyed before reaching the planetoid. (VOY: "Course: Oblivion")