One Harvard scientist hopes to find clues to immortality by studying lichens, the frilly, crusty, green growths that appear on rock walls, tombstones and old trees. For eight years, Anne Pringle, a mycologist, has been lurking about a cemetery each fall in order to keep tabs on the lichens that grow there. She hopes her results will reveal whether the strange organisms wear away with the passage of time and eventually die or whether these creatures wander into the immortality camp. The New York Times reports:

If true, such organisms would be the fungal equivalent of vampires, able to die only by external means. (“A bus can still run over them,” Dr. Pringle said.) But the concept has yet to catch on in the wider world of biology, dominated by scientists who study plants and animals.

Lichens are not actually individual organisms, but symbiotic colonies of fungus paired with either green alga or cyanobacteria (both of which photosynthesize, just like plants). Pringle is most interested in the fungi part, which some researchers suspect does not age. One giant fungus in a Michigan forest is thought to be up to 10,000 years old, for example.

In the world beyond fungi, whether organisms can escape aging is a matter of scientific controversy. A longstanding explanation for aging pins the blame on built-up genetic mutations activated once fertility begins to taper off. According to a second theory, aging occurs because some traits that make us more reproductively successful may also set the stage for our demise. High testosterone levels, for instance, might help males make more babies — but also predispose them to prostate cancer.

Neither of these scenarios apply to fungi, however. Those organisms reproduce more fruitfully as they age (and mushrooms don’t have prostates). If researchers could figure out how lichen and other fungi get around aging, those discoveries may have implications for human medicine.

Pringle’s preliminary results show that as lichens grow older and larger within her cemetery, they are less likely to die. In the coming seasons, she plans on implementing more direct experiments with the hopes of confirming the lichens’ immortality within the span of her own life.

More from Smithsonian.com:

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Saving Amphibians From a Deadly Fungus