The main structural element in the cell walls of fungi is chitin. Chitin is a complex carbohydrate that provides both strength and flexibility to the cell wall, helping to maintain the cell's shape and integrity. Unlike cellulose in plant cell walls, chitin is a nitrogenous polysaccharide, making it a unique component of fungal structure. This specialization allows fungi to adapt to diverse environments and contributes to their role as essential decomposers in ecosystems. Overall, chitin is crucial for the biological functions and survival of fungal organisms.