Illustration of a phycobilisome rod from a Synechocystis sp. cyanobacterium. Phycobilisome structures (PSBs) are light-harvesting antenna and part of the photosynthetic apparatus of cyanobacteria, or blue-green algae, and red algae. They are found on the cell's thylakoid membranes where they capture specific wavelengths of light and transfer the light energy to the photosynthetic reaction centres.