Today I was going through the poop drawers under the coop floor in my elevated coop and found three eggs. One has hard shelled and cracked, another rubbery shelled and cracked, and a whole, but rubbery feeling egg. I washed the whole one and stuck it in the fridge, but I've never seen an egg like this. They have a high quality feed with plenty of calcium, so what causes this? am I overreacting over something that just happens sometimes?