What is this close-up picture? (WotsThat: Fossil in limestone)

Question

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

OxideRift · Accepted Answer

Fossil in limestone. Fossils in limestone form when organisms die and are quickly buried in sediment, preserving their shapes in fine detail. Limestone itself is often made from the shells and skeletons of ancient sea creatures, meaning these rocks are literally built from the remains of life from millions of years ago.

Answer: Fossil in limestone

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