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Musk-Order66 t1_jdap7te wrote

Reply to comment by Gandoku in Sunrise at Phang Nga Bay, Thailand (2000x2000)[OC] by cryptodesign

Wait so if those are from a coral reef… that’s a fossil?!

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Gandoku t1_jdaqkai wrote

I think not exactly? But I'm not sure. This website explains it pretty well imo: https://www.paddleasia.com/karst-topography.htm

I'm not a geologist or anything but summarizing some of the info, Coral Polyps deposited the lime that turned into limestone ~100 million years ago. Halfway down that page is a photo of how the bottoms are more narrow than the tops on some formations as the sea levels went down and carved them out

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JimJohnes t1_jdavgk5 wrote

It's not only coral reef, it was bottom of an ocean so it's everything that had calcium- and silica-based skeletal structure, including plankton and mollusks. All limestone and chalk is made of fossils, just not in intact state.

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Elgin-Franklin t1_jdb18we wrote

The whole thing isn't a single fossil, but it is made of fossilised corals, shells, and carbonate minerals that are deposited in between them as mud.

If you can get yourself to any limestone outcrop near you there's a good chance you'll find fossils in them

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