The mechanical and chemical effects of lichens on the outer and inner surfaces of tafoni features were investigated through a multidisciplinary approach at two locations (Oasi 74°42'S, 164°07'E, 40-250 m a.s.l.; Mount Keinath, 74°32'S; 163°58'E; 850 m a.s.l.) close to the Italian Antarctic station (Mario Zucchelli). Outer tafoni roof surfaces show low values of effective porosity coupled with pervasive hyphal penetration and an extensive reddish-brown weathering rind. Inner tafoni surfaces show higher values of effective porosity, which correspond with an almost absent weathering rind and low hyphal penetration. Our observations indicate that: (a) iron oxy-hydroxides, particularly concentrated where hyphal patches and bundles contact biotite, consist of hematite; (b) the microcosms of lichen hyphae and their precipitates fill voids to form case hardening on outer surfaces; and (c) on inner surfaces biological action is less active, most likely because of more intense thermal stress and salt action.