Clonal multicellularity designates multicellularity in which all cells arise by division from a single progenitor cell, leading to a genetically homogeneous multicellular organism; in contrast, aggregative multicellularity gives rise to genetically heterogeneous entities. Clonal multicellular organisms include those in which cells form small, simple three-dimensional structures, and those in which cells form a range of tissues and structures through genetically regulated spatial differentiation. While it encompasses the largest, most conspicuous and morphologically complex multicellular plants, fungi and animals, clonal multicellularity has arisen independently numerous times in eukaryotes, archaea and bacteria.

This chapter lists the lineages in which clonal multicellularity has been reported: in the eukaryotic groups Chlorophyta (Archaeplastida), Rhodophyceae (Archaeplastida), Phaeophyceae (Sar), Chrysophyceae (Sar), Oomycota (Sar), Peritricha (Sar), Fungi (Opisthokonta) and Holozoa (Opisthokonta); in the archaeal genus Methanosarcina; and within bacteria in the Actinobacteria, Cyanobacteria, Candidatus Magnetoglobus multicellularis, and filamentous members of the Desulfobulbacea, Clostridiales, Chloroflexi, Gammaproteobacteria. It briefly summarizes what is known of the relationships between and within these lineages, and some distinctive features of multicellularity in each one.