A recent article in Discover magazine indicates that there is hope for the world’s monuments and buildings that are being ravaged by acid rain, erosion and urban pollution. “The stone falls apart grain by grain because the binding agent is lost,” says Carlos Rodriguez-Navarro of the University of Granada in Spain.

Mineralogist Rodriguez-Navarro and his colleagues have found that the common soil bacterium, Myxococcus xanthus, produces crystals that mimic the way natural calcium carbonate binds together limestone, dolomite and marble. After placing slabs of limestone from the Granada cathedral in a broth of the microbes for two weeks, the bacteria infused the surface with crystalline glue, and the whole structure was strengthened. In addition to restoring the stone, the bacteria do not clog the rock’s pores, which would speed decomposition by trapping water inside. (Editor’s comment: it will take some big stew pots to soak most monuments!)