Sheliak vessel

Star Trek: The Next Generation
Episode: TNG 149 - Ensigns of Command, The

A Sheliak vessel encountered the Enterprise-D and demanded that the Federation evacuate all human "vermin" from the planet Tau Cygna V, a planet that belongs to the alien race, as stated in a Federation treaty.

Picard negotiated with the captain of the vessel, using a clause in the treaty to buy more time to evacuate Tau Cygna V.