This textbook on biofilms combines knowledge on sub-aquatic and sub-aerial biofilms and their products (stromatolites, oolites, ore, petroleum and gas deposits). It describes how formation and degradation of minerals and rocks is achieved through biofilm formation on and in sediments, soils and rocks. Methods of study, examples of Precambrian biofilms of an early Earth as well as the most recent examples of desert rock biofilms are treated in this integrative book on biofilms, microbial mats and stromatolites.