Assemblers of Infinity, is a science-fiction novel by Kevin J. Anderson and Doug Beason
It is the 21st century. Earth's space program is thriving, with a colony in place on the Moon. And then an incredible discovery is made on the lunar farside. A massive structure is being erected by living machines---microscopically small, intelligent, unstoppable, consuming whatever they touch. All who come near them die horribly. Meanwhile, the mysterious structure continues to grow, expand, take shape. And its creators begin to multiply...