The Egyptian pyramids are a monument to human  engineering, preserving both culture and mummies   across millennia.

But for the purposes of our  microcosmic journey, what’s most remarkable about   them are the bits of fossils that made up their  limestone. As far back as the 5th century BCE,   the Greek historian Herodotus noticed  these shells embedded in the pyramids.   What he did not know is that these shells  were the remnants of creatures that are just   as intriguing as the pyramid’s own inhabitants.

In the early 19th century, far removed from those   pyramids, a young boy named Alcide d’Orbigny  would become fascinated with the tiny shells   he found on the beach. And when he grew up and  expanded his hobby into a more professional study,   he named them and the organisms they  came from. He called them foraminifera.  If you judge them just from appearances, it might  be a surprise to learn that foraminifera   is an amoeboid protist, meaning that  inside that hard shell--which is also   called a test--there is a squishy amoeba.

While we don’t know too much about how   foraminifera evolved from other eukaryotes,  we know that they’ve been around for over   500 million years. And over that time, they’ve  evolved at least 10,000 species that are still   living today and another 40,000 species  that we know only through their fossils.  There are two different main types of  foraminifera. Most of the living species   we know are benthic foraminifera, which means  they’re found throughout the ocean’s depths,   living on rocks and seaweed or just the ocean  floor.

They’ve even been found in abundance in   the Challenger Deep, the deepest known point in  the ocean. The second group are the planktonic   foraminifera, which float on or near the surface  of the ocean thanks in part to their tests.  Both types of foraminifera make and inhabit  tests. And scientists can use the materials   and test morphology to distinguish between  different species.

Some foraminifera secrete   compounds like calcium carbonate, while  others glue bits of inorganic particles   together with the organic equivalent of cement. And inside, the tests are divided into chambers,   with some species creating complex structures out  of these chambers the way we might create complex   arrangements of rooms in a building. Foraminifera  are architects, and as they grow, they build more   chambers to accommodate themselves.

Some grow  so fast they have to add a chamber every day.  The shapes of these chambers play a particularly  crucial role for planktonic foraminifera,   which generally build less complex structures  compared to their benthic counterparts.   The chambers they build are more globular,  which provides the planktonic foraminifera   with a means to stay buoyant as they float around. But foraminifera, or “forams” as they call them in   the biz, don’t just build shells, they also build  webs. Or more accurately, they become webs.

The   foraminifera tests are lined with holes that  act like little windows to allow the organism’s   pseudopodia, or “false feet” to peek out. And “peeking” might be an understatement.   The pseudopodia reach and reach out,  forming their own webs as they do to find   food and catch it. These forms of pseudopodia  are called reticulopodia, and you can see here   just how weird and extensive they are in action.

They may look like a disintegrated spider’s web,   but remember that this is the organism  reaching its own body out to the microcosmos,   spreading itself thin as it contorts into  new shapes. Zoom in on those reticulopodium,   and you can see the cytoplasm streaming  through it like a biological highway.  When forams die, the soft matter that makes  up those pseudopodia will eventually decay,   but what remains are the tests. And over the  hundreds of millions of years they’ve existed,   the death of foraminifera has become  integrated into our planet’s geology.   Large swathes of the ocean floor are covered in  the collected remains of planktonic foraminifera,   creating a dense substance called Globigerina  ooze.

And we owe famous sights like the   pink-tinted beaches of Bermuda and the nummulitic  limestone of the Pyramids to ancient foraminifera.  And the abundance of these fossilized remains  provides us with a record of our planet’s history.   While forams may be found throughout our oceans,  individual species have their own environmental   needs, whether that means they prefer a particular  temperature or salinity or light condition. So   assessing the fossil composition of different  sediments helps scientists understand what   our world once looked like. And understanding  the past shapes our present as well, with oil   companies using microfossils to understand  the geology of the area they’re working in.  So where did our fossils come from?

Well, they  had a bit of a journey. James, our master of   microscopes, got these samples from Virginia by  way of his fiancée, who collected water and sand   from the coast and packed them in a jar. If that seems like an easy enough way   to give the lovely gift of microbes to a  microscopist, just remember that she had   to take the samples from Virginia to Poland.  And that’s where things started to go wrong.  First the jar of sand and water leaked all  over her luggage.

Then after she arrived,   James’ cat tipped over the jar, as cats do like  to do. But we cannot blame the cat for all the   subsequent damage either because James also  tipped the jar over while trying to open a window.  On the one hand, this story seems like something  of a cautionary tale on the importance of   careful jar handling. But even after  having lost all that water, the jar   was still full of sand—and also what turned out  to be a whole bunch of foraminifera fossils.  And maybe that’s the true lesson to  take from our shelled, amoeboid friends:   that even when the world around them has  tipped and turned and leaked, even then   you can find something dazzling in what remains.  Thank you for coming on this journey with us as  we explore the unseen world that surrounds us.  And thank you to everyone who has so  far backed our Kickstarter project   of the Microcosmos microscope.

We’ve blown  past our goal and I’m very excited that we’ll   be sharing these with you. I’ve really  been enjoying mine. I need to make my   technique better because I’ve actually hurt  my neck a little bit looking into it so much.  Thank you also of course to all of our patrons  on Patreon.

These people whose names are on the   screen right now. These folks are the reason  we are able to make Journey to the Microcosmos.   Everyone of you, thank you so much  for giving us this opportunity   to make stuff for you and for everyone. If you want to see more from our Master   of Microscopes James Weiss, you can  check out Jam & Germs on Instagram,   and if you want to see more from us, there’s  always a subscribe button somewhere nearby.