Or M. Bialik on Nostr: Microbialites ( #sedimentary buildups formed by microbial activity) were very common ...

Microbialites ( #sedimentary buildups formed by microbial activity) were very common in the Proterozoic, but other groups took over in the Phanerozoic. But when the #environment is stressed, they come back - and we can use them to infer on past #ecological stress gradients, but also the conditions at the stressed end member.
https://www.sciencedirect.com/science/article/pii/S0031018215005404
I rather like this paper, and to me, it's one of my most underperforming as far as citations are an index. So let me highlight it once more.