Development of a Rapid Indicator of Biodeterioration of Historic Stone. Ralph Mitchell, principal investigator, and Christopher J. McNamara, of Harvard School of Engineering and Applied Sciences worked to identify microbial species for possible use as a microbiological indicator for identification of stone deterioration. The researchers compared microbial communities on deteriorated and undeteriorated stone and looked for key species associated with stone deterioration. Differences between the communities suggest that microbial indicators could provide a simple and rapid means for early detection of stone biodeterioration.