Fragmentation is a common approach when propagating macroalgae for aquaculture. Large highly branched fronds of the red algae Eucheuma, Kappaphycus, and Gracilaria are broken into small pieces, and each piece is attached to a rope. The limited number of Transcription factors in multicellular algal systems suggests that molecular cascades responsible for regulatory systems of stem cells in multicellular algae should be tractable and generate insights into developmental homologies across multicellular eukaryotic life. Eukaryotic algae are a diverse polyphyletic assemblage assigned to the kingdoms Chromista, Plantae, and Protozoa. The chapter presents representative examples of the occurrence and function of actively dividing stem cells, reactivated set-aside cells, algal cell totipotency, and capacity for regeneration among the multicellular algae. The vast majority of red algae grow by means of strict apical cell division in which apical cells have indeterminate growth. The totipotency of protoplasts obtained from a variety of red, green, and brown multicellular algae has been demonstrated in culture.