How are natural bath sponges prepared for commercial use?

Natural bath sponges are the skeletal remains of specific animals belonging to the class Demospongiae. While living, these organisms consist of a mass of cells and fibers permeated by a complex canal system, covered by a tough, dark skin.1

To prepare a sponge for commercial use, it must be harvested—typically by hooking, harpooning, or skin diving—and then thoroughly cleaned. The process requires the complete removal of the millions of living cells that inhabit the organism. Once these cells are cleared away, what remains is the soft, elastic spongin skeletal framework that is recognized as the commercial product.1

Because sponges possess the biological ability to regenerate lost parts, they can be sustainably cultivated from small fragments.1