There’s an image of a flayed human wrist wearing a watch that’s been making the rounds online. Generated by a new 3D CT scanner, the image shows bones, blood, tissue, and a faint shadow of skin around the edges. The image is amazing and also really, really gross.

It’s not unusual for CT scans — a type of X-ray imaging that produces detailed views of whole cross-sections of the body — to be in 3D. The big difference is the degree of detail: the device that produced this gory image is part of a new wave of spectral scanners that use specialized detectors to distinguish individual X-ray frequencies. That gives researchers better contrast between the matter the X-rays passed through, like bone, or flesh, or blood.

The weird wrist picture comes from the first human imaged by the MARS scanner, which is one such spectral CT setup. Anthony Butler, a radiologist at the Universities of Canterbury and Otago in New Zealand, co-invented it with his father, Phil Butler, a physicist at the University of Canterbury and CEO of MARS Bioimaging Ltd. It’s actually Phil Butler’s hand in the picture.

The idea is that, eventually, these detailed scans might help with diagnosing and monitoring cancers, bone diseases, or blood vessel problems. Other research groups have been using them in labs around the world — like to image tiny kidney stones, for example. But they’re not being used in hospitals yet. “My hope is that this sort of technology, as it winds its way through medicine, will improve the diagnosis and treatment of many of the 300 million people worldwide who annually get a CT scan,” Anthony Butler says.

Still, the watch-clad, bloody chunk of wrist was particularly disgusting to me. And I was surprised by my reaction: the technology that produced it is amazing, and I’m the person who tries to one-up my editor with disgusting pictures of botflies in Slack. Plus, I think regular X-rays have a kind of ghostly beauty to them.

So I asked disgust expert David Pizarro, a psychology professor at Cornell University, why I was so much more grossed out by this image than a typical X-ray. He says he is, too: “It’s pretty damn cool, but I do not want to see my own bones and blood like that,” he says. “I’m easily disgusted, which is a little ironic.”

He says that innards — blood, guts, body fluids — are generally pretty gross to people because disgust has evolved as a survival mechanism. “It’s an adaptation to keep us away from things that might contaminate us. Parasites, pathogens, germs, those were a reliable source of disease and death in our ancestry. They still are,” he says. And bodily fluids or open wounds could carry those things.

But since disgust generally works by pattern recognition, things that won’t make us sick — like stunningly detailed X-ray images — can still elicit the same feelings. “So this is playing a trick on our minds by showing us gore without ever having seen an injury,” he says. And the more vivid the trick is, the more effective. That’s why it’s a good thing there aren’t scratch-and-sniff versions of these images, he says.

There are downsides to disgust, Pizarro says, including that it can be damaging to patients who avoid going to the doctor for fear of grossing their clinicians out. “But they’re way beyond that,” he says. Butler agrees: going to medical school, doing operations, and working in emergency departments gives medical people a high threshold for squeamishness, he says. And a picture is low on that scale.

In fact, Butler doesn’t think that seeing the inside of his dad’s appendages is gross, at all. “The most amusing thing to me about it is that this is my father’s foot and ankle,” and it’s been shared all over the world, he says. “It’s funny to have a family member’s foot seen so many times.” He was also surprised by the detail of the pictures. Blown up to presentation size for a recent talk, he could see the wrinkles in his father’s skin, and the microstructure of the bone. “It’s fascinating, and kind of amusing, rather than gross.”

Butler attributes the attention his team’s work has received to the images that caught my eye, too. “There are other groups working on this, and they’ve done amazing things as well. We just happened to get a picture that everyone liked,” he says. “It’s a pretty picture, which is quite helpful.” I told him I wasn’t sure “pretty” was the word for it, but he stood by his description. Radiologists like him are “looking at it with the eye of how much information they get off of it. What does it show them? It’s a different type of pretty.” After all, he says, “Beauty is in the eye of the beholder.”