A weird single-celled organism has an internal organelle so massive it effectively doubles the amount of 'skin' the cell has.
April 17, 2026
Original Paper
The Anaeramoeba symbiosome: a single contiguous organelle that doubles the cell's membrane surface
bioRxiv · 10.64898/2026.04.10.717692
The Takeaway
Imagine if your lungs were so big and complex that their surface area was equal to your entire body’s skin; that’s basically what’s happening inside Anaeramoeba flamelloides. It has a single, continuous organelle called a 'symbiosome' that wraps around its internal partners to help them share energy. This organelle is so massive and folded that it has as much surface area as the cell's entire outer membrane. This bizarre cellular architecture was a complete surprise to biologists, as it’s a level of internal complexity rarely seen in such simple life forms. It shows that even 'lowly' microbes can build massive, intricate internal 'factories' to survive in extreme environments.
From the abstract
Anaerobic protists across diverse lineages have independently evolved intimate spatial associations between their hydrogen-producing mitochondrion-related organelles and prokaryotic symbionts, yet the cellular structures mediating these syntrophic partnerships remain poorly characterized. Anaeramoebae - a recently described phylum of anaerobic amoeboflagellates - have evolved a particularly elaborate solution: the symbiosome, a membrane organelle that houses sulfate-reducing Desulfobacter sp. sy