Germlings were grown from Monostroma latissimum Wittr. reproductive cells on nylon ropes. Holdfast threads and some uniseriate filaments were observed to have penetrated the fibers of the dispersed ropes. The algal filaments were easily isolated and prepared for cultivation, in comparison to the methods of enzymatically isolated algal protoplasts. Under low light (60–100 μmol photons · m−2 · s−1), the algal filaments grew to form a filamentous mass. When cultivated under stronger light (300–600 μmol photons · m−2 · s−1), they grew to initially form tubular thalli and then, when cultivated under light intensities >700 μmol photons · m−2 · s−1, formed foliaceous thalli. Consequently, the filaments were homogenized into small sections and then sewed on the nylon rope for algal mass cultivation. Under high-intensity natural light, they grew to form leafy thalli.