The acquisition of photosynthesis in eukaryotes occurred through the engulfment of a photosynthetic bacteria to form an endosymbiosis, where one cell (symbiont) lives within another (host). This initial event gave rise to the chloroplasts, the photosynthetic organelles of algae and land plants which ultimately transformed the global ecology and chemistry of our planet. In subsequent events, endosymbioses between eukaryotes spread photosynthesis throughout the tree of life. To understand the complex evolutionary transition to photosymbiosis it is essential to compare and contrast multiple independent acquisitions of photosynthesis across the tree of life. Meringosphaera is a genus of unicellular eukaryotes that has been placed in the group centrohelids. This group is heterotrophic, yet Meringosphaera is considered photosynthetic based on its microscopically observed autofluorescent "green bodies". Thus, the overall aim of this project is to determine the exact nature of these endosymbiotic bodies, identify their closest free-living relatives, and characterize their cellular, genetic and metabolic integration.