A cyanobacteria may be evolving organelle like characteristics

https://www.uri.edu/news/2024/04/evolution-in-action-new-study-finds-possibility-of-nitrogen-fixing-organelles/
Nitrogen is a nutrient essential for all life
on Earth. Although nitrogen gas (N2) is
plentiful, it is largely unavailable to most
organisms without a process known as nitrogen
fixation, which converts dinitrogen to
ammonium — a major inorganic nitrogen source.
While there are bacteria that are able to
reduce dinitrogen to ammonium, researchers at
the University of Rhode Island, Institut de
Ciències del Mar in Barcelona, University of
California at Santa Cruz and the Massachusetts
Institute of Technology have discovered
nitrogen-fixing symbiotic organisms exhibiting
behaviors similar to organelles. In fact,
researchers posit these symbiotic organisms –
UCYN-A, a species of cyanobacteria – may be
evolving organelle-like characteristics.
...
paper here
https://www.sciencedirect.com/science/article/pii/S009286742400182X
Metabolic trade-offs constrain the cell size
ratio in a nitrogen-fixing symbiosis