Dormant, written by A. E. Van Vogt, is set in the years immediately following the end of the Second World War and the first atomic explosions. The hero (if it can be called that) of the story is a giant slab of rock, which turns out to be a sentient machine that has lain dormant at the bottom of the sea for untold millions of years until it was woken by trace amounts of radioactive energy as a result of nuclear fallout in the ocean. When this 400-foot slab of rock climbs out of the sea and up a hill, it attracts the attention of the US military, which ultimately decides to destroy it with an atomic weapon. The sudden flood of energy was all Iilah (for the rock had a name) needed to wake up fully and remember its mission; after which, it destroys itself in a gigantic explosion, dislodging the Earth from its orbit and causing it to plunge into the Sun. For Iilah’s purpose was to destroy a solar system. And even if it had known that the war it was designed to fight ended eons ago, robot bombs are not designed to make up their own minds.
This story was written by Van Vogt in the 1940s but much to my delight, I just came across a sequel published on the Web in 2012. Written by a Bruce Munro and titled After Dormancy, it gives humanity, in the author’s own words, “a slightly happier ending…”