A multidisciplinary study of silicified volcanoclastic, near-shore deposits from the 3.446 Ga “Kitty's Gap Chert,” Warrawoona Group, Pilbara, reveals that they contain a wealth of carbonaceous microbial fossil remains. The volcanoclastic sediments host predominantly colonies of coccoidal microorganisms that occur in two modal size ranges, 0.4–0.5 μm and 0.75–0.8 μm. These microbial colonies coat the surfaces of the volcanic particles and form either dense, carpetlike associations up to tens of micrometers in diameter comprising hundreds of individuals. They also form less dense concentrations that include many chainlike associations of coccoids. All colonies are associated with a polymer film (extracellular polymeric...