FIG. 8.

Mud volcano as a window into a subsurface biosphere. Petrographic images of clasts from various terrestrial mud volcanoes in transmitted light, showing foram-like microfossils (arrows) in pore spaces. Blue is tinted epoxy that fills porosity. Black material in chambers of some of the microfossils is pyrite, which may suggest that sulfate-reducing bacteria also lived in microhabitats within porosity of the mud volcano clast. (A–B) Bozdag mud volcano, Azerbaijan. (C) Nirano mud volcano, Italy. (D) Wushanding mud volcano, Taiwan. Image credits: D.Z. Oehler.