First, you take a fresh clean sponge out of the package.
What do you use it for?
Maybe dishes, or wiping the tables and counters.After a while, the sponge gets pressed into service for some less appealing task; perhaps bathroom or floor cleaning. It will now be unfit for use for food surfaces.
Finally, the old sponge meets its end days, doing some nasty task, like cleaning up cat barf from the carpet.