ehhh shells made of calcium ye thick c**t grits for there gizzard to grind there food thick c**t!!!!!!!!!!!! Lol, at old timer and blue one, funny they eat it every day but don't end up with a full crop! Perhaps the grit mixes with the food it has ground and so is passed down into the digestion and is used as part of the structure of the shells. Don’t feed it and they lay soft shelled eggs, funny that. No one said shells don't contain calcium just that they would add little to the diet. A normal diet either complete or raw will supply more than enough calcium. As I said likely do no harm or g