A type of specialized fungi, lichens, are the pioneer and predominant life form in harsh land environments on Earth with strong tolerance to extreme environment, including both extant and fossilized materials. Multiple spectroscopic techniques have been widely used in extreme-environment and planetary detection and life detection. Herein, multiple spectral methods and Energy Dispersive Spectrometer (EDS) analysis were applied to test whether lichens could be the potential biomarkers and might contain the detectable biosignatures as life signal in extreme environments and on exoplanets (such as Mars). Our results indicated that Infrared spectroscopy (IR) and EDS techniques are effective for micro-region analysis of fossil components, which could distinguish fossil and rock substrates by characteristic spectral bands and elemental component contents. More importantly, C–O stretching in phenyl and C–H stretching were detected in both extant and the 165-million-year fossil lichens by IR, which are the basic skeleton constituting the characteristic lichen secondary metabolites. Raman spectroscopy successfully identified characteristic peaks corresponding to chlorophyll and carotenoids in extant lichen samples, but strong fluorescence interference hindered its application to fossil samples. Similarly, Laser-induced breakdown spectroscopy (LIBS) analysis detected emission peaks of CN and C2 in extant lichen samples but failed to detect these organic components in fossil samples, likely due to the loss of organic materials during fossilization. Despite limitations, integrating multiple spectral techniques is crucial for comprehensive exoplanet and extreme environment life detection missions. This study suggested that lichen can be utilized as a potential biomarker for searching the Martian and extreme environmental life, as its characteristic aromatic compounds will be the practical biosignatures lasting 165 million years. Furthermore, our study emphasizes the potential of infrared spectroscopy, among other techniques, for in-situ biosignature detection in extreme environment and on exoplanets (such as Mars), offering valuable insights for future exploration. Keywords: Extreme environment · Lichen fossil · Biosignature · Multiple spectroscopy · Aromatic compounds.