In my kitchen I keep two empty yogurt containers. One is for used coffee grounds and the other is for egg shells. Egg shells have so many uses in my home and garden that it doesn’t make sense to just compost them. I mash them down and use them mostly in the garden where they help protect my plants from slugs and they’re also a great source of calcium, plus they reduce the soil acidity. Egg shells are also great as a non-toxic abrasive cleaner to use on pots and pans, shower doors and grout. IF you’ve got a metal thermos with stains, you can combine egg shells with hot water, then shake well. The mixture helps break down stains.