Scientists Say They’ve Discovered ‘Little Lab Zombies’—Seemingly Immortal Tissue Taken From Sea Cucumbers

Chunks removed from the marine creatures more than three years ago haven’t degraded and show signs of biological activity, raising questions about what it means to be alive

June 2, 2026 3:56 p.m.

a green blob on a dark background — A microscope image of tissue taken from a sea cucumber. The green coloring indicates cellular activity. Sara Jobson

Scientists have stumbled upon what they’ve dubbed real-life “zombies.”

These seemingly immortal things—amputated tissue from the sea cucumber species Psolus fabricii—appear to exist in a gray zone of life. The discovery, described in a study published on May 27 in the journal Science Advances, could be useful for future research but also raises philosophical questions about what it means to be alive.

Sea cucumbers are an ancient type of spineless creature that sit on the ocean floor. They’re known for their remarkable regenerative powers; some species can be split in half, after which the separated sides will regrow their missing parts.

The variety involved in the new study, P. fabricii, lives in the cold water of the Atlantic and Arctic Oceans. And its potential “tissue immortality” was discovered by accident.

When a researcher was removing a sea cucumber from its lab tank, some of the invertebrate’s tube feet—tiny appendages used to move across the seafloor—detached from the body and remained stuck to the glass, study co-author Sara Jobson, a marine scientist at Memorial University of Newfoundland in Canada, tells CNN’s Jacopo Prisco.

This process isn’t as horrifying as it sounds. Detachment is a natural defense mechanism used by sea cucumbers, similar to how lizards lose their tails to escape predators. But researchers typically expect the leftover body parts to rot, especially in a nonsterile environment.

“We noticed that [the tube feet] were still there after a couple of days, and then weeks, and then months, and they were still stuck on,” Jobson says. “They were healing, and they even grew a little bit. They were surviving in their natural environment.”

a white blog with a small red center at the top, and a semi-transparent blog with a larger reddish center — Tissue from a tube foot one year after it was removed from the sea cucumber, shown on top, compared with several years after removal, shown on the bottom. The shift from red to lighter white and pink indicates pigmented cells have formed healthy tissue. Sara Jobson

So, Jobson and her colleagues amputated tube feet from three sea cucumbers and kept them in a tank with flowing seawater. The severed tissue has now survived for more than three years and, within that time, has shown evidence of immune activity, cell division and diversification, and tissue reorganization. Experiments suggest that the cells take in nutrients by absorbing amino acids, building blocks of proteins, dissolved in the water.

But what, exactly, are these severed tissue chunks that show signs of life but aren’t animals themselves?

“We often call them, lovingly, our little lab zombies,” Jobson tells Scientific American’s Cody Cottier. “Because we don’t know: Do they count as alive? Do they count as dead?”

In addition to lacking both a mouth and a gut, they don’t reproduce. Nevertheless, they are biologically complex pieces removed from animals, and they can potentially carry on forever. “We haven’t seen any signs that they’re degrading or dying,” Jobson adds.

The findings represent the first known case of long-term survival and growth of abandoned tissue in a natural setting, the authors write in the paper. Scientists can keep some things perpetually alive in highly controlled environments, such as cell lines, each of which is a group of dividing cells originating from a common ancestor. Sometimes they can continue dividing indefinitely, and they are important research tools.

“While regeneration itself is not new in these animals, what this study demonstrates—something that could be described as ‘tissue immortality’—is entirely novel,” Noé Wambreuse, a marine biologist at the University of Southampton in England who did not participate in the study, tells CNN.

Did you know? Some sea cucumbers shoot out their insides

Certain species of the strange marine animal will eject a stringy organ out of their rear ends when a predator scares them. The organ, which can be silky and sticky, contains proteins with features similar to those of amyloids, proteins implicated in neurodegenerative conditions including Alzheimer’s disease, researchers reported in 2023.

But it might be too soon to call these tissues immortal, Alejandro Sánchez Alvarado, a molecular biologist and president of the Stowers Institute for Medical Research, tells Scientific American. Researchers will need to investigate their DNA sequences called telomeres—the endcaps of chromosomes that shorten each time a cell divides—to determine whether the tissues truly might live forever, says Sánchez Alvarado, who wasn’t involved in the study.

Still, the possibly immortal tissue could help scientists develop more accessible, easier-to-manage cell lines. And it shows the wonders of nature that scientists have yet to explore.

“This discovery highlights that the ocean holds profoundly unexpected biological innovations,” says Andrea Bodnar, a marine biologist and science director of the Gloucester Marine Genomics Institute, who was not involved in the study, in a statement.

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