2. After the eggs cool, crush them with a rolling pin. They become really brittle and break like glass. Be careful - the pieces are pretty sharp.
3. Keep crushing until the pieces are very small. Now they don't look or smell like an egg shell and are ready for the chickens.
I put all of our food scraps in my compost pile. The chickens know that scraps are there and will scratch through my pile to look for food treasure. They aerate and fertilize my compost pile while looking for something to eat. I just put the crushed egg shells on the ground near the compost pile and they know they are there and can eat them as needed.
There you have it - egg shells in place of oyster shells for backyard chickens. You never know when you might need this information...