Fig. 2.

Cryptoendolithic features of hyphae and weathering of zeolite and calcite. Back-scattered Environmental Scanning Electron Microscopy (ESEM)-images (a–d, f) and Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM)-section (e). (a) Heavily wheathered cowlesite (zeolite mineral) covered by hyphae (now mineralized). (b) Chemical weathering front in the contact between fungi and cowlesite. (c, d) Hyphae penetrating micro-fractures into calcite. Only the central strand of the hyphae is remaining in most parts. (e) SRXTM cross-section showing hyphae between cowlesite grains and within cracks in the minerals. (f) Biofilm on mineral surfaces with hypha extending out from the biofilm. Scale marker bars are 200 µm (a), 30 µm (b), 40 µm (c), 20 µm (d), 300 µm (e) and 10 µm (f)