Is this a bird egg?

[Isadora]

UPDATE: After 18 days, I decided to remove the nest and eggs… whatever kind they were. I had noticed a spider web around the eggs. Since it was undisturbed for several days, I knew nothing was attending the eggs. So it was time for the nest and eggs to go. As I started removing the nest, I heard a familiar thud as the eggs shifted. It was the undeniable thud of a wooden egg. Yes. Something had build a nest around 4 wooden eggs that I had used last year to “teach” my chickens where to lay. So there you have it. I wasted 18 days waiting for wooden eggs to hatch. That should give you a good chuckle for today.
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That is amazing