This experimental series of space craft were designed to be equipped with trans-metaphasic shielding which was capable of withstanding conditions that would destroy most other starships. Through the use of this form of special shielding, the Jellyfish was capable of moving through more dangerous terrain and survive it such as the interior of a star. They were designed for use by a single occupant with the vessel being the size of a shuttle craft. It contained a warp drive which was able to attain warp eight as well as two weapon arrays at the front of the ship.
The design of this starship was a product of the engineering knowledge of Geordi La Forge in conjunction with the Daystrom Institute, as commissioned by the Vulcan Science Academy in the 2380 decade. The ship was created with the intention of being used as part of scientific as well as exploration missions. Starfleet was working with the creators of the ship in order to determine which of the ship systems were capable of being adapted for use by the Federation. (ST website: The Path to 2409; ST - Countdown comic: ; TOS movie, novelization & comic adaptation: Star Trek)
In 2387, the ship was modified during the Hobus Crisis when the unstable star threatened to create a shockwave that would destroy entire worlds in its path with Romulus being the first planet facing a possibility of destruction. The Jellyfish was modified in order to carry the Red matter compound and was programmed to allow Ambassador Spock to pilot the craft. This allowed him to reach the star and deploy the red matter thus causing the star to collapse into a singularity.
However, he was too late as the Hobus star caused a shockwave that destroyed Romulus killing millions of Romulan lives. Spock managed to arrive at the star and deploy the red matter thus causing it to collapse into a singularity but before he could escape, the Jellyfish was intercepted by the vengeful Nero and his ship the Narada. The two craft were pulled into the singularity where they were seemingly destroyed. (TNG comic: "Countdown")
Both the Narada and Jellyfish ended up in the past: the Romulan vessel in 2233 instantly creating an Alternate reality and the Vulcan vessel in 2258 of the new reality. Nero captured the Jellyfish, however a landing party of James T. Kirk and Spock managed to take the vessel back. Spock piloted it, Suicide ramming the Jellyfish into the Narada, igniting the red matter and creating a black hole. (TOS movie: Star Trek)
- There are at least three different sources on the creation of the Jellyfish. Countdown states it was Geordi La Forge when the Path to 2409 states it was La Forge in conjunction with the Daystrom Institute and the Star Trek XI movie states it was the Vulcan Science Academy.
- This could be explained that in the movie, the ship was commissioned by the Vulcan Science Institute. Which means that it was actually built by La Forge and the Daystrom institute, but it was either put in service, or it was officially put into active service by the Vulcan institute.