plastids in other organisms, glaucophytes have a peptidoglycan layer that suggests the endosymbiotic origins of plastids from cyanobacteria . Glaucophytes contain the photosynthetic pigment, chlorophyll a . Like the red algae and Cyanobacteria, the glaucophytes harvest light via phycobilisomes , structures made mostly of phycobiliproteins . The green algae and land