The cells of Paralia sulcata are cylindrical in shape and have a width greater than their length. They are heavily silicified, meaning they contain a significant amount of silica. These cells join together to form chains of varying lengths through marginal linking spines and interlocking ridges and grooves found on the flat valve face. These linking structures can be observed in water mounts. There are two types of valves in this species: separation valves that lack the linking spines, and linking valves.The external openings of the strutted processes are visible as granules when viewed under a light microscope. Additionally, numerous chloroplasts can be seen as small disc-like structures in light micrographs.