The simplest of the Volvocaeans are ordered assemblies of cells, each similar to the related unicellular protist Chlamydomonas and embedded in a gelatinous matrix.
In all Volvocaceans, the fertilization reaction results in the production of a dormant diploid zygote (zygospore) capable of surviving in harsh environments.
Once conditions have improved the zygospore germinates and undergoes meiosis to produce haploid offspring of both mating types.
Immediately after, the cell layer is inside out compared with the adult configuration—the apical ends of the embryo protoplasts from which flagella are formed, are oriented toward the interior of the plakea.
The mechanism of inversion has been investigated extensively at the cellular and molecular levels using a model species, Volvox carteri.