Multicellularity evolved through two mechanisms; simple multicellularity and complex multicellularity. Both processes evolved through Eukaryotes, however complex multicellularity evolved to only six clades. In complex multicellular organisms, there is cell-cell adhesion, an intercellular communication system, and the process of regulatory genes facilitating how tissues are distinguished. Simple multicellular organisms have cells that are either grouped in clusters, sheets, or balls. These cells originate from a mitotic division with one progenitor. There is no tissue facilitation, but there is the differentiation of reproductive and somatic cells. Unlike their complex counterparts, cell communication and transport is limited. Unlike simple multicellular organisms, complex multicellular organisms are organized in a three-dimensional way that allows some of the cells to directly interact with the environment.…show more content… It is very important for the cells to be able to interact with the environment, because the organism must be able to transport oxygen, nutrients, and signal molecules required for internal and external cells. Also, complex multicellularity has evolutionary advantages that simple multicellularity does not. Complex multicellular organism are able to diffuse more efficiently and have a more precise cell-cell communication system, and tissues that are able to facilitate bulk transport. Complex multicellular organisms are the most common. Some prokaryotes also show simple multicellularity, however there are none with complex multicellularity, which could be due to the fact that prokaryotes lack organelles, so they lack the metabolic energy it takes to sustain and duplicate a large genome. That, and prokaryotes have less gene regulation cells than