The monstrous space aliens in Roald Dahl's Charlie and the Great Glass Elevator. The "K" is NOT silent: "k'nid". I recall that they were described as "vermicious", although now it seems Dahl just liked the sound of that adjective, since knids are more like Shmoo or Plastic Man than like worms. They are unharmed by hard vacuum, but are quite vulnerable to the blazing heat of reentry.