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# The Sun Got the Byline on Earth's Iron. Microbes May Have Ghostwritten It.
- URL: https://www.gottabekidding.me/the-sun-got-the-byline-on-earths-iron-microbes-may-have-ghostwritten-it/
- Published: 2026-10-21T10:04:00.000Z
- Updated: 2026-10-21T10:04:00.000Z
- Description: Earth may once have iced over pole to pole, yet its seas kept stacking up iron. Whatever did the work never needed daylight, and something like it may still be on the job.
- Author: Deep Time
- Tags: Earth Sciences

Under Antarctica's Larsen C Ice Shelf, in seafloor mud that sunlight and oxygen never reach, lives a bacterium that appears able to turn dissolved iron into solid iron. It may help explain how Earth kept making iron deposits while sealed under ice.

Banded iron formations, rocks striped with iron and silica, are usually credited to ancient photosynthetic bacteria. Those microbes oxidized iron in seawater, the thinking went, and the iron sank and accumulated.

That explanation has a winter problem. Some formations date to Snowball Earth, a stretch of the Neoproterozoic when ice is thought to have entombed the entire globe. Photosynthesis needs light, and light does not pass well through that much ice.

Korean researchers turned to a core of mud the icebreaker Araon pulled in 2013 from 324 meters, or 1,063 feet, down near the ice shelf. It holds roughly 12,000 years of history, and some layers resemble the ancient striped rock.

From DNA in that mud, the team rebuilt the genome of an unknown bacterium that lives on chemistry rather than light, provisionally called Candidatus Mariimomonas ferrooxydans. It sat at the hub of the buried community, while two other microbial groups took turns dominating, a rhythm that could account for the stripes.

Its genome carries a gene for a protein called Cyc2\. Added to E. coli, the gene made those bacteria rapidly turn dissolved iron into an insoluble form that settled out. Over long spans, such fallout could build iron minerals.

The findings suggest this dark route may reach back to the Archean, before photosynthesis of any kind existed.

A microbe that has never seen daylight may have been doing the sun's job under the ice. How much of the planet's iron it deserves credit for is unknown.

**Read the full story at** [Phys.org, October 7, 2026](https://phys.org/news/2026-10-snowball-earth-iron-deposits-microbes.html?ref=gottabekidding.me)

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**Hot Take:** A banded iron formation records what was made, never who made it. Geology, like most institutions, tends to credit whoever works in daylight.