## 2 Materials and Methods  
Six small samples, three for geological and three for microbiological studies, were collected under the supervision of the restorers (Figure 2). Mineralogy and textural properties of samples were studied on (30 \(\upmu\)m-thick) polished thin sections on a transmitting light microscope. A staining procedure with combined alizarine red S and potassium ferric cyanide solution was applied to distinguish ferroan and non-ferroan calcite and dolomite phases [1]. Two thin sections were made from the sample, one from the external surface of the sample and the other being transverse to that surface. Photomicrographs were performed by using a petrographic microscope: Zeiss Assioskop, a digital camera: USB UI-1490 SE and an image capture software: uEye Cockpit (IDS). The sample was also studied under a scanning electron microscope (SEM) using BSE mode on a Hitachi S3000N SEM coupled with an X-ray detector, Bruker XFlash 3001, for microanalysis (EDS) and mapping. The samples' observation was carried out under variable pressure mode without coating with any conductive material. EDS analyses were performed at a 40 Pa chamber atmosphere, 20 kV accelerating voltage and 10-12 mm working distance. The mineralogical composition was analyzed by powder X-ray diffraction in a Bruker D8 Discover A25 microdiffractometer. Microdiffraction X-ray equipment makes it possible to make precise measurements in very small areas without the need to prepare the sample. The analysis area was selected using an optical microscope and an X-ray micro-source with a copper anode, using its K\(\alpha\) spectral line. EVA and TOPAS computer programs were used for data processing and qualitative and quantitative identification, with the Rietveld method, of the crystalline phases present in the sample. Figure 1: The Cross of the Inquisition before (**A**), after the vandalism (**B**), and restored (**C**). For the identification of the organisms two approaches were adopted in this study. First, due to the fact that the vandalized fragments of the Cross were stored for two years, and no fresh samples from organisms could be obtained, we focused our attention on the identifications of DNA on the fragments available, in order to determine past biological colonizations. In addition, we sampled the lichen community colonizing the City Hall limestones in an area around 5 m from the Cross. It was expected that the community or at least the most abundant lichens in both the building facade and Cross would be the same. The protocols used were as follows:  
Nucleic acids from each sample were extracted with commercial extraction kits, following the manufacturer's instructions. FastPrep matrix-E lysis tubes (Qbiogene, Carlsbad, CA, USA) with glass beads were used and physical disruption was performed using a shaker (Fast Prep-24, Solon, OH, USA) at a speed of stirring at 5.5 m/s for 2 \(\times\) 30 s. The extracted nucleic acids (50 \(\upmu\)L for each sample) were stored at \(-\)80 \({}^{\circ}\)C until shipment for sequencing. The concentration of the DNA extracted from the samples was measured by fluorometric quantification using a Qubit 2.0 fluorimeter (Invitrogen, Carlsbad, CA, USA). Eukaryotes were identified by sequencing the 18S ribosomal RNA gene. The genes were amplified by PCR using the primer pairs EUKA (5'-AACC CTG GTT GAT CCT GCC AGT-3') and EUKB (5'-TGA TCC TTC TGC AGG TTC ACC TAC-3') for eukaryotes. Amplifications were carried out in an iCycler thermal cycler from BioRad (Hercules, CA, USA). Reactions were set up in 0.2 mL tubes (Greiner BioOne, Monroe, LA, USA). Each reaction contained: 5 \(\upmu\)L of 10\(\times\) BioTaq PCR buffer (Bioline, Randolph, MA, USA), 1.5 \(\upmu\)L of MgCl2 (50 mM stock solution), 1 \(\upmu\)L of a mixture of the four nucleotides (dNTP) (2 mM) (Invitrogen, Carlsbad, CA, USA), 0.5 \(\upmu\)L of each of the primers with a concentration of 50 \(\upmu\)M, 0.25 \(\upmu\)L of the equivalent BioTaq DNA polymerase (Bioline, Randolph, MA, USA) at 2.5 units and template DNA.