There are a surprising amount of uses for eggshells that don't include simply discarding them. Some of my favorite recommendations include: To deter pests: this works particularly well for snails/slugs, as they don't like traversing through the sharp shell pieces. Add to compost: the eggshell minerals are a great addition to homemade compost. As a fertilizer: if you're a gardener, you'll probably know better than me what plants thrive best with the addition of eggshells. Turn into eggshell powder: sterilize, dry, and crush the shells into a powder that can be used in several ways. Check here for more ideas on how to use leftover eggshells.