Lifeburst

Description for LIFEBURST by Jack Williamson:

Somewhere, eons past, the seekers had begun as weapons—cyborg war machines. nuclear explosions, and powerful lasers meant little to them, for each was larger than 10 battleships and subsisted on a diet of heavy metals, preferably radioactive. Soon the seekers began their own Lifeburst, flying to nearby stars, evolving, eating, destroying...our solar system next.