Figure 4

Electron images of SRB microstructure. (a) and (b) No nitric acid (HNO3)–etched FeS2. (c–h) 70% HNO3 etched FeS2. (a) Micro-hydrothermal vents. (b) Layered structures at the edges of the FeS2. (c) HNO3-etched layered structures of the FeS2 edges. (d) and (e) Backscattered electron image of spheroidal SRB fossils. (f) and (h) Backscattered electron image of filamentous SRB.