Multicellular morphogenesis is the main content of myxobacterial social behavior. The morphogenesis contains aggregation of cells under nutrient deprivation, autolysis, development of fruiting bodies and formation of myxospores. There is a complicated system of signals and regulation during morphogenesis, which is much more similar to eukaryotes. Myxobacterium is an important model for studying cellular differentiation and development in prokaryotes and biological evolution.