Researchers Identify "Ancient Home" Microbe in Shark Bay Providing Visual Proof of Eukaryotic Origins

UNSW researchers find an Asgard archaeon in Shark Bay, providing the first 3D visual evidence of how simple cells began the journey toward complex life.

By: AXL Media

Published: Apr 10, 2026, 8:02 AM EDT

Source: Information for this report was sourced from EurekAlert

A Microscopic Window Into the Dawn of Complexity

The transition from simple single-celled organisms to the complex eukaryotes that comprise all plants and animals remains biology’s greatest mystery. Associate Professor Brendan Burns and his colleagues at UNSW Sydney have identified a pivotal actor in this evolutionary drama: a member of the Asgard archaea living within the ancient microbial mats of Shark Bay. These "living fossils" provided the necessary environment to observe Nerearchaeum marumarumayae, a microbe whose lineage is closely tied to the ancestors of humans. The discovery suggests that stromatolites served as more than just a cradle for early life, acting instead as a laboratory for the cellular partnerships that redefined the biosphere.

Visualizing the First Cellular Partnerships

For decades, the endosymbiotic theory which posits that complex cells formed when an archaeon engulfed a bacterium lacked direct physical evidence of such interactions. The research team utilized electron cryotomography to generate high-resolution 3D images of these microbes at a scale of one-millionth of a millimetre. These images revealed a physical link between the Asgard archaeon and a bacterium through fine, tube-like structures known as nanotubes. According to Associate Professor Debnath Ghosal, this provides the first visual confirmation of physical cooperation between these two distinct domains of life, mirroring the suspected origins of mitochondria.

The Collaborative Chemistry of Survival

The difficulty in cultivating these organisms in a laboratory setting underscores their fundamental reliance on inter-species cooperation. A/Prof. Burns suggests that the inability to grow Asgard archaea in pure culture stems from their total dependence on bacterial partners for essential vitamins and nutrients. In exchange, the archaeon provides compounds like hydrogen that the bacteria utilize. This metabolic exchange is facilitated by elaborate tube-like structures and chains of vesicles sprouted by the archaeon, creating a "microbial village" where collective survival is prioritized over individual isolation in the harsh conditions of Shark Bay.