What is this close-up picture? (WotsThat: Robin egg shell texture (macro))

Question

What object is shown in this zoomed-in close-up photo?

BogIron · Accepted Answer

Robin egg shell texture (macro). A robin's egg gets its blue-green colour from a pigment called biliverdin, laid down as the egg forms, and stronger colouring is thought to signal a healthier mother bird to her mate.

Answer: Robin egg shell texture (macro)

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