Does anyone know how long it will take for shells to get hard if they suddenly got soft. Today, I notice when I went out to check for eggs, that there was an egg and it was soft. I thought that the layers feed had oyster shell in it. I went out and bought 50 lbs today and gave them in a separate feeder. Also, just wondering how do they know they should eat oyster shells in the first place.... any answers would be welcome.