The Symbioship was Power Girl's Kryptonian Rocket.
History
Pre-Crisis
On Earth-Two, Kara Zor-L was sent to Earth from the dying planet of Krypton by her parents to protect her younger cousin Kal, but the symbioship travels more slowly, and she arrived on Earth decades after her cousin has landed. The symbioship was designed to keep her in stasis during her development through the prolonged voyage, and by the time she arrives on Earth, Kara is shown to be in her early twenties.
Dawn of DC
See Also
Links and References