The last existing Tarellian ship was encountered by the Starship USS Enterprise-D on Stardate 41294.5 whilst in orbit round the planet Haven. Prior to this encounter the Tarellians where thought to be extinct. Most Tarellians where wiped out by a genetically engeered virus produced during a civil war on their home planet. Some, however, fled the planet taking the virus to other planets only to infect the native population. The surviving ships where hunted down, with what was believed to be the last ship being detroyed by the Alcyones eight years prior to the encounter.

The most notable feature of the Tarellian ship is the large ionic fusion reactor which accounts for over one quarter of the mass of the vessel. This reactor is in excess of 180 metres in diameter and demonstrates the vast size such reactors need to be in order to yeald enough power to run even a rudimentary warp drive. In comparison a typical federation matter / antimatter reactor is a mere 3-5 metres in diameter.

The warp drive on the ship encountered by the enterprise had failed and thus it was only able to operate at sub-light speeds. The fact that it made it to planet Haven, a journey of more than eight years, in this condition is something of a testiment to the resiliance of the ship.