Random Microorganism Generator

What the random microorganism generator does

Every living thing in this list was completely invisible to every human being who ever lived, for almost the entire span of human history, until one man in a Dutch town looked through a bead of glass and saw them moving.

Press the button and it hands you one: a bacterium, a virus, an amoeba, a diatom, one of the tardigrades that survive being frozen and boiled, one of the cyanobacteria that quietly built the air you breathe. What follows is the story of how we found out any of them were there, and how badly we underestimated them once we had.

Please note: this is an educational tool, not medical or laboratory-safety advice. If you have a health concern about an infection, please speak to a qualified healthcare professional.

How to use it

1. Choose how many you want. One if you are deciding, more if you are browsing.
2. Press Generate. A fresh draw every time.
3. Press Copy to take the set with you.

The kingdom nobody could see

For all of human history until about three hundred and fifty years ago, nobody knew that microorganisms existed. Not that they were poorly understood. Nobody knew they were there at all.

Think about what that means. A drop of pond water is crowded with living things, hunting and swimming and multiplying. The plaque on your teeth is a teeming city. The soil, the air, your own gut, all of it packed with life, and for thousands of years of human civilisation, through every empire and every great thinker, none of it was visible to anyone. An entire kingdom of living things, quite possibly the majority of all life on Earth, sat directly in front of every human who ever lived, and no one could see it, because it was simply too small.

People had guessed at something. When food spoiled, when disease spread, some suspected an unseen cause. But guessing is not seeing, and there was no way to see. The living world, as far as anyone knew, was the world you could look at: plants, animals, and the things large enough to notice. The idea that there was another whole tier of life beneath the threshold of vision was not so much disbelieved as unimaginable.

And then, in the 1670s, in the Dutch city of Delft, one man crossed that threshold, and he was not a scientist.

The cloth merchant who found it

His name was Antonie van Leeuwenhoek, and by trade he was a draper, a seller of cloth. He had no university education, no training in what we would call science, no Latin, the language of learning at the time. He measured linen for a living.

And that trade is, wonderfully, exactly how he stumbled into the invisible world. Cloth merchants used small magnifying lenses to inspect the quality of fabric, counting the threads to judge its worth. Leeuwenhoek became fascinated by lenses, and he taught himself to make them, and he turned out to have a gift for it that verged on the uncanny. His lenses were tiny, single beads of glass mounted in little metal plates, nothing like the elaborate microscopes of the learned societies. But they were better. Far better. Some could magnify a specimen a couple of hundred times or more, sharp and clear, and nobody else in the world could match them.

So he started looking at things. Pond water, and found it swarming with tiny creatures he called animalcules, little animals. Rainwater. Scrapings from his own teeth, in which he described a whole population of moving living things, the first human being ever to see bacteria. He looked at blood, and at a hundred other things, and everywhere he looked he found detail and life that no one had ever imagined was there.

When he reported all this to the Royal Society in London, the great scientific body of the age, they did not believe him. How could they? A tradesman with no credentials was claiming to see living creatures smaller than anything in the natural philosophy of the day, using instruments he would not fully explain. It sounded impossible. So in 1680 the Society sent people to Delft to check, and they looked, and it was all true. Every word.

Leeuwenhoek became the father of microbiology almost by accident, a cloth merchant who found the largest hidden thing in all of biology because he wanted to count threads more accurately. And he kept one secret to the end. He never told anyone his best method for making those extraordinary lenses, and when he died the technique died with him, so that for many years afterwards no one could see quite as clearly as the draper of Delft had.

Whose planet this actually is

Here is the part that reframes everything, and it is the reason the invisible kingdom matters far more than its invisibility might suggest. Those animalcules are not a curious footnote to life on Earth. In a real sense, they are life on Earth, and everything you can see is the footnote.

Start with time. For roughly the first half of the entire history of life, there was nothing but microorganisms. Billions of years in which the only living things on the planet were single cells too small to see. Animals, plants, everything visible, arrived extremely late, near the end of the story. Microbes are not a side branch of life. They are the trunk, and the visible world is a few young twigs at the very top.

Then consider the air. The oxygen you are breathing right now was not always here. The early atmosphere had almost none. It was microorganisms, the cyanobacteria in this list, that spent unimaginable stretches of time pumping out oxygen as a waste product until they had utterly transformed the planet's air, an act of terraforming by the invisible that made all larger life, eventually including you, possible. You are breathing the exhaust of microbes, and you could not exist without it.

And consider yourself. Your body contains a staggering number of bacteria, in your gut and on your skin, and by cell count they rival the number of your own human cells, very roughly one for one. You are not a single organism so much as a walking ecosystem, a coalition of your own cells and an enormous population of microbes that help you digest, defend and function. In a strict headcount, you are about as much microbe as you are you.

So the list this generator draws from is not a catalogue of small oddities. It is a sample of the dominant form of life on this planet: older than everything, more numerous than everything, running the chemical cycles that everything else depends on, and, until a cloth merchant in Delft ground the right piece of glass, entirely unseen. We think of ourselves as living in a world of plants and animals. We are actually living in a world of microbes, and only recently found out.

Where these come from

The organisms are drawn from a list our team researched and checked by hand, spanning bacteria, archaea, viruses, protists, fungi and more, so these are real groups and species rather than approximations. Your browser picks from them at random. Nothing you do here leaves your device.

Questions people ask

Was a cloth merchant really the first to see microbes?

Yes. Antonie van Leeuwenhoek was a draper in Delft with no formal scientific training, and his expertise with the magnifying lenses used to inspect cloth led him to build single-lens microscopes better than any others of his time. In the 1670s he became the first person to observe and describe bacteria and other microorganisms, which he called animalcules.

Why did other scientists doubt him?

Because his claims seemed physically impossible and he was an outsider with no credentials who would not share his lens-making method. Seeing living things that small was beyond what the era's instruments could normally do, so the Royal Society sent observers to Delft to verify his findings, which they fully confirmed.

Is it true I have as many bacterial cells as human cells?

Roughly, yes, by current estimates the two are of a similar order, very approximately one to one. Older claims that microbes outnumber your own cells ten to one have been revised down, but the underlying point stands: your body is host to an enormous microbial population and functions as much as an ecosystem as an individual.

Did microbes really create the oxygen we breathe?

In large part, yes. Cyanobacteria produced oxygen as a by-product of photosynthesis over vast stretches of early Earth history, gradually transforming an atmosphere that had almost none into the oxygen-rich air that later, larger life depends on. It is one of the most consequential things any organisms have ever done to the planet.

Are viruses actually alive?

That is genuinely debated. Viruses, several of which appear in this list, sit at the border of life: they carry genetic material and evolve, but cannot reproduce on their own without hijacking a living cell. Whether that counts as being alive depends on how you define life, which is one of the reasons they are so scientifically interesting.

References

1. Antony van Leeuwenhoek, Pioneer of the Microscopic World. CDC Emerging Infectious Diseases. https://wwwnc.cdc.gov/eid/article/32/6/26-0531_article
2. Antonie van Leeuwenhoek. Britannica. https://kids.britannica.com/students/article/Antonie-van-Leeuwenhoek/47611
3. Antonie van Leeuwenhoek: father of microbiology. PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC10458164/