The term algalmat that is traditionally used in long time was changed into the term microbial mat and was widely adopted, which is resulted from the conceptual transformation of the blue—green algae that should be grouped into cyanobacteria. Longtime researches and studies indicate that the microbial mat is actually a complex microbial community, and this microbial community is actually a consortium of varied kinds of symbiotic/syntrophic organisms that embrace all metabolic pathways that ever emerged on Earth. Although there are some disagreements, an important idea that carbonate stromatolites were the constructs of algae mats (microbial mats) urges sedimentologists to seek the imprint of microbial activities in terrigenous clastic rocks. The reinterpretation for some problematic trace fossils that were found in the early times results in emergence of some new concepts such as the mat ground and the matground structure. Also, more and more observations of the microbialmat relative features within clastic rocks led to a new recognition, i.e. the microbial induced sedimentary structure (MISS) can be grouped into a fifth category of primary sedimentary structures. On the basis of emphasizing that microbial mats influence the depositional fabric of clastic deposits across a wide range of physical, chemical and biological processes, the microbial induced sedimentary structures can further be grouped into several genetic categories that contain the microbialmat growth, the metabolism, the disruption, the decomposing and the diagenesis types. The establishment of both the genetic type and the classification for the microbialmat feature that are left in clastic rocks promote the development of the microbialmat sedimentology in clastic rocks and within the framework of geobiology.