Was there a yolk inside this part?
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Looks like 2 eggs there to me, one with shell more fully formed. I assume you found a completed yolk in it too? Looks like they landed on feathers that stuck to the moist egg. Sometimes a tiny feather will be stuck to an egg, as a possible clue to who laid.
After they have had breakfast outside, I like to go in the henhouse to clean up their poo and feathers, and invite any in who want to return. I tap on suggested nest boxes to explore and toss in fresh shavings or hay, and several seem to stick around to inspect nests. I back off and sing or speak in a soft voice to encourage them to relax and scratch around and let nature take its course. Some of the girls seem to like someone else lingering around quietly as they explore nests. Once they settle in, I tiptoe away tho...and they can hear I'm nearby outside on protective Roo duty. 3 are skilled daily or almost daily nest-box layers already in their first week, so I observe when they head toward the henhouse and leave them alone. Love it when their schedule is so consistent I can go out and find a fresh warm egg when expected! I like to give attention and reward soon after laying also so they feel like the Top Chick and enjoy the new daily routine.
MIne are mostly Brown layers so I am watching times/size and color patterns closely. I misplaced the Oyster shells in the build the Coop shuffle - but I'd been saving free-range store eggshells for feed supplement. I try to observe if the crushed eggshells I stack and scatter for them are disappearing, and their enthusiasm for them, to gauge if I should offer more.
Mine are new layers who have loved grape leaves and other greens since about week 5, with full ration of commercial Starter feeds first thing in the morning and with snacks mid-day and late afternoon. My feed has been corn and soy-free non- GMO Starter crumbles from Kalmbach in early weeks, then BarAle pellets which they hated until I added water to it, next month - BarAle's awesome Wild Bird mix as snack, after a full morning ration of Crumbles Week 14-18. From week 18 on - Scratch-N-Peck (pre-lay) Grower whole Grain feed, with handfuls of Bar Ale mix added - a month before their first eggs at week 20. The BarAle Seed mix keeps regular feeds interesting, and the Whole Grain Scratch n Peck is now offered side by side with layer feed, so they can choose. After first eggs, Kalmbachs layer crumbles were offered to known layers, and to any who wanted the 2nd week, as I'm not totally sure who may have laid a yard egg or in the box without my knowing she was there. I make sure they all have at least an hour of sun a day and a dry place to flop for dust AND sunbathing - as getting D3 is important for calcium metabolism. All have had firm intact looking shells - but I think they still need more calcium as a couple seemed to break easily. In the 2nd week of laying one egg has been much larger (or sneakily produced by the largest Barred Rock - but I can't imagine her being quiet or undramatic about ANYthing - so how could i miss it?!) At least 5 of my 7 are laying, at wk 21 - and I'm excited to go out to check on them even in cold weather. Good luck - and have fun!