Do you remember the previously ubiquitous COVID strains BA.4, BA.5, or BQ.1.1? Have you heard of the currently surging XBB.1.5, and do you understand what the tangle of letters and numbers mean? You probably don’t—and some experts say it’s because of the convoluted names. You could be forgiven for thinking another strain of Omicron poses no new threat—especially if you’ve already had Omicron or received the new Omicron booster.

New strains of Omicron are becoming increasingly more transmissible and evasive, with the ability to dodge immunity from prior vaccination and infection. And using the term “Omicron” or something like XBB.1.5 to describe them just isn’t cutting it anymore, Dr. Ryan Gregory, a biology professor at the University of Guelph in Ontario, Canada, told Fortune.

“Kraken” is what he calls XBB.1.5, which the WHO just declared the most transmissible Omicron variant yet. For months, Gregory has worked to offer up “street names” for complicated COVID strains, in a bid to better communicate the evolving Omicron threat to the public.

And as pseudonyms go, he’s got a lot more where the Kraken came from.

With input from both professional and “citizen” scientists around the globe, Gregory has compiled a list of memorable monikers from Greek mythology and other realms— Chiron, Argus, Basilisk, and Typhon—for the Omicron spawn that medical experts believe pose the greatest threats in the near future. He told Fortune he was inspired by a Twitter user who dubbed the Omicron strain BA.2.75 “Centaurus” this summer, and saw the media and some experts pick up the moniker.

Since Gregory began using Kraken—an aggressive sea monster from Scandinavian folklore—shortly after Christmas, it’s quickly gained steam, as reported by Bloomberg. The term has been picked up by a host of other international and national news outlets including Insider and Sky News. Centaurus was named in journal articles and used by the likes of Nature and the Guardian. And some variant trackers are now using the proposed names as hashtags on Twitter.

Gregory likened Omicron and its variants to different species within the mammal family of vertebrates.  

“If you said, ‘Oh, what’s that thing in my yard?’ and I said, ‘It’s a mammal,’ you’d say, ‘Is it something that will eat me? Will it steal my vegetables? Does it carry disease? Is it somebody’s pet?’” he explained.

“Omicron” remains a useful descriptor, he maintained. But more than a year after the highly transmissible strain burst onto the global scene, someone needs to name new, concerning variants. 

If the WHO won’t, he’s decided he will.

Gone are the days of Greek letters?

When COVID variants began materializing, the WHO devised the strategy of naming them after Greek letters, skipping some that might be confusing—like Nu, which sounds like “new,” which would apply to all variants at some point—or offensive to some, like Xi, the surname of China’s president.

Generally, the approach worked, Gregory said. But Omicron muddled matters. 

Dr. Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark., is on Gregory’s informal team to develop nicknames for particularly troublesome Omicron spin-offs. 

Even as a seasoned scientist and professor, Rajnarayanan said he’s found it difficult to effectively communicate with nonscientists regarding the tangled mess of variants scientists are monitoring.

“When you keep calling 200 different lineages of different potential the same name, it becomes a problem,” he recently told Fortune.

Experts like Gregory and Rajnarayanan worry that a lack of a new and specific names for Omicron variants could lead members of the public to draw false conclusions—like that the virus isn’t evolving, or that a months-ago infection with Omicron will confer protection against newer strains of Omicron, which isn’t necessarily true.

‘The public can’t keep these numbers straight’

So far, the WHO has declined to give particularly concerning Omicron variants a Greek letter. Fortune reached out to the international health organization to ask why and didn’t receive a response.

Its resistance is based in science, since new Omicron variants can be traced back to older Omicron variants. But it’s not practical, Dr. Eric Topol, a professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute, told Fortune last fall.

“And it’s not a good defense for not naming them,” he added. “I would implore them to do so. The public can’t keep these numbers straight.”

Topol says he would have called BA.5, dominant globally until recently, Pi or Sigma because it’s “so distinct” from the original Omicron, BA.1, as well as the so-called stealth Omicron, or BA.2.

Two particularly worrying recent variants—BQ.1.1 and XBB—should also be assigned Greek letters because researchers have called them “extreme in terms of immune-evasiveness and resistance to monoclonal antibodies,” he said at the time.

“They could be given new Greek letter names instead of the ones some people invent,” he said of the new strains. “If different people are going to make up names, it’s going to be just as confusing as the numbers or letters.”

Basilisk here, Hydra there

When describing potentially threatening variants, the WHO currently uses so-called Pango lineages—combinations of letters and numbers you’ve likely heard of, like BA.2.75.2 and BA.4.6.

Pango labels have maintained their specificity as the virus mutates unrestrained, Gregory said. But such labels are almost too precise for the general public. And aside from being forgettable, they’re easily confused.

“When I talk to people, I say BA.1, they think I’m saying BL.1—and that’s a different variant,” Rajnarayanan said. “Even the two-letter system causes confusion.”

Gregory equates Pango names to technical species names, like Mus musculus for mouse or Rattus norvegicus for rat. Such technical names aren’t often used by the general public. Some species of animals, however—like Oncorhynchus mykiss, or rainbow trout—get a common name because “we encounter them a lot, they’re important to us, they’re dangerous or useful or delicious or whatever,” he said.

And so it should be with COVID variants, he contends. Particularly rampant, “high-flying” variants like XBB, a blend of BJ.1 and BM.1.1.1, should get a nickname—Gryphon, per his system—for ease of communicating the threat to the general public.

It’s especially important, he says, as a menagerie of Omicron spawn spike in different locations around the world in a fashion unlike any seen in the pandemic so far.

“If we want to make it clear that what’s rising in the U.K. is not the same as what’s rising in the U.S.—the ‘alphabet soup’ is going to be very difficult for that,” he said. He’s convinced that if his system was adopted, with, say Basilisk and Cerberus in the U.K., and Hydra and Aeterna in the U.S., “you can immediately recognize which names are the same and which are not.”

If COVID keeps spawning new mutations, there are other lists of names to tap—planets, stars, constellations, galaxies, Gregory said.

What in the world will he think of next?

[This report has been updated to correct a reference to the name of China’s president, Xi Jinping.]