“Mothership” was a song developed for 1997’s Pop album.
In the book U2 by U2, Bono talks about the starting foundations of “Mofo” revealing it had gone through a couple of name changes:
It was as if my whole life was in that song. Electronic blues death rattle. It takes the cliché insult ‘motherfucker’ and turns it into something raw and confessional. It went through some bizarre titles, ‘Mothership,’ ‘Oedipussy’. It contains the most exposed moment in the hardest song on the record.