The SF trope “Big Dumb Object” was coined for any mysterious, large, and often powerful object discovered near the beginning of a novel and used as plot device. Originally, it helped build the “sense of wonder” that used to be part of popular SF. Nowadays we’re just too jaded for BDOs, alone, to have much impact. Too bad. It seems like we’ve lost something important in our modern sophistication and worldliness… If you’re interested, Wikipedia can give you a start on the BDO trope and its uses.