Cellulose Sponge is made up of cellulose from wood pulp and cotton fibers. It is durable, reusable, and biodegradable. After its useful life, cellulose easily returns to the soil. Experiments show that these remarkable sponges can be recycled as mulch, to cover newly planted grass seed, as well as other sustainable uses. In the outdoor elements, the cellulose will break down over time and become part of the earth, making these sponges a very earth friendly ‘green’ renewable resource.