You're supposed to need a microscope to see bacteria, right? Not Thiomargarita magnifica.

This giant cell is clearly visible to the naked eye, having the size and shape of a human eyelash.

Now classified as the world's biggest bacterium, T. magnifica was discovered living on sunken, decaying mangrove tree leaves in the French Caribbean.
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Centimetre-long T. magnifica is not the largest single-celled organism on Earth. That's probably a type of aquatic alga called Caulerpa taxifolia which is 10 times longer still. But the bacterium is definitely impressive when you consider there are many, much more complex life forms on Earth that require some sort of magnification to be observed. Think of those really teeny worms and flies out there.

https://www.bbc.co.uk/news/science-environment-61911817

A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles

We usually think of bacteria as microscopic isolated cells or colonies. Sampling a mangrove swamp, Volland et al. found an unusually large, sulfur-oxidizing bacterium with a complex membrane organization and predicted life cycle (see the Perspective by Levin). Using a range of microscopy techniques, the authors observed highly polyploid cells with DNA and ribosomes compartmentalized within membranes. Single cells of the bacterium, dubbed Candidatus Thiomargarita magnifica, although thin and tubular, stretched more than a centimeter in length. —MAF

Abstract
Cells of most bacterial species are around 2 micrometers in length, with some of the largest specimens reaching 750 micrometers. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized Candidatus (Ca.) Thiomargarita magnifica, a bacterium that has an average cell length greater than 9000 micrometers and is visible to the naked eye. These cells grow orders of magnitude over theoretical limits for bacterial cell size, display unprecedented polyploidy of more than half a million copies of a very large genome, and undergo a dimorphic life cycle with asymmetric segregation of chromosomes into daughter cells. These features, along with compartmentalization of genomic material and ribosomes in translationally active organelles bound by bioenergetic membranes, indicate gain of complexity in the Thiomargarita lineage and challenge traditional concepts of bacterial cells.

https://www.science.org/doi/10.1126/science.abb3634