soft eggs

   Welcome to the site mshort.

The marble sized eggs are called wind eggs and don't have any yolk.  Think they can be formed when the hens system is tricked into thinking a yolk has been released by a bit of grit etc.

If you feed your hen primarily on layers pellets, cut out the treats including excessive greens and have crushed oyster shell available at all times this should help.  If your hen is young and just started to lay things should improve as she gets the in the swing of things.  Some older hens lay soft shelled eggs when they are coming to the end of their laying time.  Just keep an eye out for any signs of ill health as soft shelled eggs can break inside the hen and cause infection/death.