Lazarus' spaceship was a domed, single-person timeship used by the time traveler Lazarus and his antimatter universe counterpart to travel through time and between different dimensions of space. Powered by dilithium crystals, the ship provided access to the negative magnetic corridor, allowing travel to and from the antimatter universe.
On stardate 3087.6, the USS Enterprise encountered Lazarus and his ship on an uncharted planet after experiencing a "winking out" of the universe, when, for a moment, everything ceased to exist. After Captain Kirk forced the insane Lazarus into the negative magnetic corridor, his ship was destroyed by phaser fire from the orbiting Enterprise, forever sealing the corridor. (TOS: "The Alternative Factor")