Colonies attached to their natural substrate show individual organisms, common discharge opening, and stolons which assist the organisms in fixation and locomotion. Time-lapse sequences show the extension and the retraction of the stolons, assisted by internal ampullae, as well as the locomotion and division of entire colonies. In the following: various cell types located in the mantle, and selected internal organs from individual organisms, such as the central nervous system, the pharynx, the gastrointestinal tract, and the heart as it reverses its beating direction. The vegetative reproduction of the new abdomen and thorax from seperate primordia is further elucidated by showing buds in various phases of development. Demonstrating sexual reproduction, oocytes, semi-developed and fully developed larvae are shown while swimming. Once anchored to a substrat, metamorphosis begins, during the course of which the larval tail soon is retracted. The film closes with the newly founded primary colony extending its feet and crawling around.