Introducing The Scutoid — A Newly Discovered Shape Hiding Inside Our Bodies

Just when we think we have discovered, and mastered, every shape in the world, comes the scutoid. The three-dimensional, prism-like structure has been hiding in plain sight in all living creatures, including humans. While not visible to the naked eye, scutoids, the shape skin cells take as they bend, twist, or turn, are everywhere – in your armpits, elbows, organs, and even all over your face.

The team of scientists, led by Universidad de Sevilla biologists Pedro Gómez-Gálvez and Pablo Vicente-Munuera, stumbled upon the scutoid while investigating the epithelial cells, which line the outer surface of our skin and inner surfaces of most internal organs. More specifically, they were trying to determine how the tissue that protects our bodies from harmful microbes remain so tightly packed despite being subjected to the twists and turns as organs grow, or as we move our limbs. Previous research had indicated that the epithelial cells accomplished the task by aligning themselves in a bottle or column shape.

However, when the researchers tried to simulate the shape using computer modeling and imaging techniques they found the cells take on a much more complex form – one they could not classify among the ranks of those that already existed. “When we found the shape, we said, let’s talk to the mathematicians – for sure they know the name of this,” Javier Buceta, a systems biologist and co-author of the study, said. “But they couldn't give us a name, because it didn't have a name. We had to find one!”

After some deliberation, the scientists, who think the shape resembles the scutellum, a part of an insect’s thorax, decided to call it scutoid (pronounced SCOO-Toid). While naming it was easy enough, they now had to confirm the computer-generated shape existed in nature. With the help of microscopy and computer imaging, they were able to confirm that the epithelial cells of fruit flies and zebrafish were indeed scutoid-shaped.

So what exactly is a scutoid? In their study, published in the journal Nature Communications on July 27, 2018 the scientists describe it “as a shape that has two ends, both of which it could stand on and looks vaguely like a prism, but with six sides on one end, five on the other, and a strange triangular face on one of the long edges of the prism.” Confused? You are not the only one. University of Seville biologist and study co-author Luis Escudero also had a hard time describing the new shape. It was only after he modeled it in Play-Doh for his daughter that it became clear.

The classification as a “new shape” has caused a few experts to argue that the scutoid has been around all this time and hence should not be called “new.” Matthew Gursky, a professor of mathematics at the University of Notre Dame, states, “To me, it makes no sense to say that something is ‘new’ if you just happened to be the first person to describe it. I realize that by that argument there are no new species (barring those that evolve into distinct, previously nonexistent species)—there are only newly discovered species. To that I say: yes. I think that finding out about a frog that you didn’t know about before doesn’t make it new—it just makes it new to you.”

Regardless of how it is classified, the scutoid, which plays a vital role as a building block of multicellular organisms, may prove useful to scientists trying to grow artificial organs and tissues. Buceta says, "For example, if you are looking to grow artificial organs, this discovery could help you build a scaffold to encourage this kind of cell packing, accurately mimicking nature's way to efficiently develop tissues." Useful as it may be, we sure hope this crazy-looking, hard-to-define shape does not get added to geometry textbooks and make the already difficult subject even more so!

Resources: smithsonianmag.com,thenewyorker.com,forbes.com