Here's a diatom (alga in a glass case), probably Cymbella sp. (apparently also called "rock snot"...), sitting atop a stalk of mucilage. These diatoms can sometimes be seen on rocks in creeks and streams as fuzzy brown stuff growing, comprised of large colonies. In masses, they are also extremely slimy -- perhaps you have unknowingly received damage from these critters making you slip and fall. The brown stuff is the plastid itself, taking up much of the cell -- you can almost make out the thylakoid stacks as fine striations on the top part, where the plastid curls towards you, providing us with a handy cross-section. Energy is stored in the fat globules seen in the middle of the cell. The very centre contains the nucleus, which is not visible in this section. Diatoms are much thicker than we like to imagine them, sometimes thicker than they are wide. Surrounding the frustule (glass case) is more mucilage, seen as that faint outer contour. This probably is what makes their masses exceptionally slimy -- you're stepping on layers and layers of glass cases embedded in balls of mucus. In other words, avoid stones covered in brown fuzz when crossing rivers -- to prevent crushing innocent colonies, of course, rather than anything to do with self-preservation.
The views expressed are those of the author(s) and are not necessarily those of Scientific American.
I first encountered the wonders of the protist realm back in childhood, when a murky droplet of pond scum was revealed by the microscope to entail an alien world in its own right. It took another decade to discover there was a field and a community dedicated to these organisms, and I bade farewell to the study of more familiar big things. As a kid I was also fascinated by tales of exploration of the New World, as well as those of fantasy worlds. I was then sad that the age of surveying new landmasses on earth was over, and that human extraterrestrial adventures are unlikely to happen within our lifetimes. It seemed everything was discovered already. But that could hardly be further from the truth -- all that is necessary to begin one's own Age of Exploration is a new approach or perspective, and a healthy does of imagination. Since reality has conjured far more than the human mind alone ever could, science yields a way to write stories much wilder than fiction. All one needs to access the alien world of microbes around (and inside) them is a shift of scale by simple glass sphere.
I'm currently finishing up my undergraduate degree in Vancouver and in transition career-wise, hopefully to end up in graduate school soon. I was born in Russia (and speak the language) and spent most of my life in US and Canada. In addition to protists, I'm fascinated by evolution, including that of culture and languages, diversity and biology of cells and how they self-organise, linguistics and anthropology, particularly of the less talked-about cultures, sociology of science and plenty of totally random things that snag my attention.
Banner image was kindly post-processed and enhanced by my friend: an accomplished comic artist who goes by Achiru.