Credit: Pathologie Nordhessen
A cross section (measured in centimeters) of a calcified nodule found in a skeleton dating to Byzantine Troy, sometime around the 13th century. Cracking open the nodule, researchers discovered extraordinarily well preserved microfossils — mineralized ‘ghost cells’ — that closely resembled bacteria from the genus Staphylococcus, a family that includes many pathogenic species. The ghost cells yielded enough DNA for researchers to fully reconstruct their genomes.