If you put chalk under a powerful microscope—white cliffs of Dover type chalk, not the modern blackboard variety—you will see something like this
Because it's not just a rock. It's an accumulation of ancient skeletons: the armored husks of single-celled, ocean-dwelling plankton
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These tiny photosynthetic creatures, known as coccolithophores, are extremely abundant. When their populations boom they can turn England-sized swaths of ocean an ethereal turquoise—a phenomenon visible from space
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Coccolithophores are crucial to the ocean’s food webs, produce huge amounts of breathable oxygen, and have the power to alter the Earth's geology and atmosphere. Scientists are studying how they might sway climate change and vice versa
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per , the photo of coccolithophores is by Jeremy R Young of UCL. See nature.com/articles/natur & genome.jgi.doe.gov/Emihu1/Emihu1. & ucl.ac.uk/earth-sciences
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A passage from Thomas Henry Huxley's 1868 lecture/essay "On a Piece of Chalk"
ebooks.adelaide.edu.au/h/huxley/thoma
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absolutely! we perpetually walk on, and swim through, and breathe in creatures living and dead. we are made of Earth and much of Earth is made of us
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Is the creature a single disc or the whole ball. And if a disc why did if form ball shapes?
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a coccolithophore is a tiny drifting plant-like organism that consists of a single spherical cell. it produces discs of calcium carbonate & covers itself with them, like scales on a dragon's egg, forming the armored spheres you see in the photo
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Originally writing chalk was made of Dover-type chalk (which is still available), but today it's mostly made of gypsum, a mineral that can look quite spectacular depending on the type and how you image it micro.magnet.fsu.edu/primer/techniq
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