Scientists Uncover Strange New Life Forms Inside Human Bodies That Don’t Fit Any Known Category of Living Things

Thousands of unidentified RNA-based entities have been uncovered within the human microbiome, challenging long-standing biological taxonomies. These replicating molecules, present across diverse populations, are invisible to conventional classifications and may hint at previously overlooked mechanisms in microbial ecosystems.

The structures, newly described by a team of molecular biologists and computational researchers, were first detected in metagenomic datasets collected from human saliva and gut samples. Early evidence shows that these RNA-only elements do not behave like viruses, bacteria, or any recognized genetic agents.

A growing number of researchers are now examining whether such entities represent a distinct branch of biological replication, operating independently of protein-based systems and potentially tracing back to ancient molecular processes.

Thousands of Novel Rna Loops Identified in the Human Body

In late 2025, a research team led by Andrew Fire at Stanford University reported the discovery of over 3,000 distinct RNA structures, termed obelisks, embedded in bacteria residing within human-associated microbiomes. These elements were detected across a wide array of publicly available sequencing datasets, most frequently in samples from the oral cavity and gastrointestinal tract.

Published as a preprint on bioRxiv, the study noted that obelisks are circular, non-coding RNA molecules. They do not encode proteins, lack a protective shell, and are not associated with any known viral or bacterial genome features. Their discovery was further detailed in The Daily Galaxy’s coverage, which emphasized their potential role as a new class of life-like replicators.

These RNA loops exhibit several characteristics that separate them from other genetic elements. They form closed RNA circles, similar in appearance to viroids, which are small infectious agents that affect plants, but with important differences. Viroids are known to hijack host cell machinery to replicate and often trigger immune responses. Obelisks, by contrast, appear to coexist within bacterial genomes and show no clear pathogenicity or immunological impact.

Researchers employed custom bioinformatic tools designed to detect circular RNA signatures within metagenomic data. After extensive filtering to eliminate artifacts, the team identified conserved sequence motifs and structural patterns across thousands of samples. The results suggest that obelisks are not sequencing errors or cellular byproducts, but replicating entities that have evolved alongside microbial communities.

Classification Remains Unresolved

Obelisks do not conform to existing definitions of plasmids, viruses, transposons, or any recognized mobile genetic elements. They do not possess genes for protein synthesis or capsid formation and lack mechanisms typically associated with replication, such as RNA-dependent RNA polymerases. As a result, their replication process remains unclear.

A broader discussion on the issue of classification appeared in Royal Society Open Science, which published a 2025 review on replicating RNA structures across ecosystems. The paper highlighted how molecular discoveries like obelisks challenge the current boundaries used to define life and underscore the need for new taxonomic frameworks to describe non-coding, non-protein-based replicators.

Current microbial classification systems, such as those used by the International Committee on Taxonomy of Viruses (ICTV), are not designed to accommodate protein-free, genome-integrated RNA elements that do not function like parasites or symbionts. As such, the obelisks occupy a grey zone in biological nomenclature. This has prompted debate over whether they represent a novel domain of molecular life.

Despite their novelty, no evidence currently links obelisks to adverse effects on human health. Still, their ubiquity in core microbiome systems—especially the gut, which is essential to immunity, metabolism, and neurochemical signaling—raises questions about their indirect functional roles. Their stability across samples and potential adaptation to specific bacterial lineages may indicate evolutionary importance.

Cross-Disciplinary Collaboration and Investigative Focus

Although not named as contributors to the obelisk study, several researchers involved in related microbial and virome research have shaped the broader context in which discoveries like this emerge.

At the University of North Carolina, Dr. Mark Peifer investigates how cell adhesion and cytoskeletal dynamics regulate tissue architecture. His research into developmental biology and molecular signaling helps contextualize how foreign RNA loops might interact with cellular structures in bacteria or host systems.

At Ohio State University, Dr. Matthew Sullivan leads the Center of Microbiome Science and is widely recognized for his work on marine RNA viruses. His lab has developed machine-learning tools such as VirSorter2, capable of detecting novel viruses in complex environmental samples. These techniques, originally designed for marine ecosystems, are now being repurposed to mine human microbiomes for genetic outliers, potentially including obelisks and related structures.

Their combined contributions reflect the importance of cross-disciplinary bioinformatics, which merges evolutionary biology, genomics, and data science to reveal structures that earlier generations of sequencing technology could not detect.

Implications for Evolutionary Biology and Life’s Origin

The discovery of protein-free, self-replicating RNA loops in the human microbiome echoes concepts from the RNA world hypothesis, a widely discussed model for the early evolution of life. That hypothesis proposes that early life forms relied entirely on RNA for both genetic storage and enzymatic activity before the evolution of DNA and proteins.

Obelisks may represent either modern vestiges of that ancient biology or a parallel system of minimalistic genetic replication that evolved independently. Their existence in stable microbial ecosystems implies that nature may tolerate, or even benefit from, molecular elements that operate with radical simplicity.

Unlike viruses, obelisks do not cause cell lysis or overt manipulation of host functions. Instead, they may persist through genome embedding, a survival strategy more commonly associated with transposable elements. It remains unknown how they are transmitted between bacterial hosts, whether through horizontal gene transfer, viral co-packaging, or other pathways.