Cholesterol is a fatty substance - a "sterol" - in modern eukaryotes including plants and animals. During the Boring Billion we had fossil evidence of eukaryotic algae (~1340 Mya, adopting chloroplasts) but not of the expected sterols. Now it seems the timespan has got a bit less boring: they went looking for something like a sterol, and found it.
These protosterol lifeforms might actually be an uncharted bacterial lineage rather than eukies; keeping in mind that sometimes bacteria and eukaryotes can form symbiosis, as with the aforementioned chloroplasts, or for that matter mitochondria.
At 800 Mya the para/protosterol was replaced, by a more Darwinian breed of life. The researchers are unsure on how the modern form was any improvement over the earlier form. I wonder if they'd considered nitrates.
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