In 2077, the alien probe "Messenger" crashed into the Pacific Ocean. The adaptive nanorobot it carried ran out of control due to a programming error, and began to devour the earth's carbon-based ecology in the form of silicon-based life forms. They disintegrate 70% of urban buildings within three months, transform the ocean into a conductive colloid, and form floating "rust clouds" of nanoclusters in the atmosphere, forcibly silicifying those who come into contact.
