The Shoal spaceship was the rigged spaceship which the Shoal of the Winter Harmony planned to use to destroy the whole of New York City.
Noting that the lights weren't on, the Twelfth Doctor and Nardole visited the ship, where they encountered a pair of Shoal droids.
Grant stopped the ship from crashing into New York by acting as a buffer. The Doctor had Grant throw the ship into the sun where it would be harmlessly destroyed. (TV: The Return of Doctor Mysterio)