When their planet was attacked by a squad of Frieza's army led by Cui, a group of children led by a boy named Zeshin managed to escape in the Mirror spaceship. The fact that the ship was made of mirrors (and thus invisible) was the only reason why they managed to escape from Frieza's men blockade during the attack on their planet. Two weeks after the kids passed Namek, they attack and capture the Nameless Namek's spaceship inside their invisible spaceship. After the passengers of the Nameless Namek's spaceship, Gohan, Krillin and Bulma, save the mirror ship and its passengers from a meteor swarm, the kids let them leave and Zeshin even gives Bulma the coordinates for a shortcut to Namek.
Video game appearances
The Mirror spaceship appears in Dragon Ball Z II: Gekishin Freeza. The player can get secret information here.