These are poop bags.
They will store poop. They shall store poop. Poop is their destiny. Poop is their religion. Poop is their fate. They shall contain it, hold it in their emptiness, and give it meaning. Poop, their purpose, their all, shall be finally deposited into the rubbish bin.
There, their deed be done, and they shall sleep the eternal sleep, having fulfilled their poopiness.