Assemblers of Infinity
by Kevin J. Anderson and Doug Beason (Published by Bantam Spectra and Analog)
Nominated for Best Novel in 1993
The crew of Moonbase Columbus make an amazing discovery on the far side of the Moon—a massive alien structure is erecting itself, built up atom by atom by living machines, microscopically small, intelligent, and unstoppable, consuming everything they touch. The mysterious structure begins to expand and take shape, and its creators begin to multiply.