One all-natural sea sponge (soap not included) approximately 4 inches.
Once a month, soak in a solution of 1 cup warm water and 1 tablespoon baking soda. This will help keep the structure of the sponge intact.
Squeezing the sponge is ok, but avoid wringing and twisting the sponge. Use with gentleness when wet, as it tears easily when wet. Allow to air-dry completely between uses.
Avoid bleach and other harsh chemicals. If desired, you can soak in 1 cup of warm water and 1 Tablespoon of apple cider vinegar to disinfect.