Can some-one please tell me as it's driving me mad.Went to collect eggs the other day and in among them was the tiniest egg I've ever seen,quite literally it wasn't the size of a marble and a really dark brown.Son says must be a wild bird got in and laid it,but one egg, and this time of year?It was nowhere near sparrow egg size and I've trawled the internet and not found anything remotely like it.Could one of my hens really have laid anything that small[trying to hint about dieting maybe?]or can anyone give a suggestion. P.S. it's not a wrens egg either,much too solid & dark brown matt colour.