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Images: What Doomed the Stromatolites?

A living multi-chambered foraminiferan within a modern-day stromatolite from Highborne Cay, Bahamas. It appears bright green because it has been labeled with CellTracker Green™. (Photomicrograph by Joan Bernhard, Woods Hole Oceanographic Institution)

Postdoctoral investigator Anna McIntyre-Wressnig (left) and geobiologist Joan Bernhard of WHOI collecting mud samples near Shark Bay, Australia. Bernhard studies foraminifera in a variety of habitats, including oceanic sediments and stromatolites. (Photo by Virginia Edgcomb, Woods Hole Oceanographic Institution)

WHOI microbial ecologist Virginia Edgcomb and geobiologist Roger Summons of the Massachusetts Institute of Technology, co-authors of the current study, with samples of stromatolites they collected from Shark Bay, Australia. (Photo courtest of Richard Sperduto)

A living thecate foraminiferan, with a plump cell body and numerous thread-like pseudopods (extensions) that it uses to capture prey and explore its surroundings. Thecate foraminifera produce a soft, organic sheath around themselves. (Photo by Joan Bernhard, Woods Hole Oceanographic Institution)

A pair of micro-CT scans of stromatolites that had been seeded with thecate foraminifera six months prior. The sample on the left had been treated with colchicine to prevent the foraminifera from developing pseudopods. The fine layers of sediment characteristic of stromatolites can be seen near the top of the sample. In the sample on the right, the foraminifera were allowed to make pseudopods. The fine structure of the sample has become clumpy and jumbled.

(Photo courtesy of Leeann Louis, Beth Israel Deaconess)