Tiny RNA “obelisks” found living inside us Hidden world scientists never knew existed

Just when scientists think they have mapped the human body, nature throws in a surprise. Hidden within the microbes that live inside us, researchers have uncovered mysterious RNA entities unlike anything seen before. Dubbed “obelisks,” these tiny loops challenge long-held assumptions about life, viruses, and what might still be lurking unseen inside the human body.

For decades, biology has neatly divided life into familiar categories: bacteria, viruses, and more complex organisms. But a recent discovery suggests reality is far messier. While analysing massive genetic databases, researchers stumbled upon thousands of strange RNA molecules that didn’t match any known life forms. These entities, now called obelisks, are smaller than most viruses and behave in ways that defy existing definitions, Earth.com reveals.

The discovery was led by Nobel Prize–winning biologist Andrew Fire of Stanford University, who helped identify these unusual RNA circles while scanning genetic material from human-associated microbes. The findings were posted on January 21 on bioRxiv, immediately drawing attention from scientists studying microbial life.

“It’s insane,” says Mark Peifer, a cell and developmental biologist at the University of North Carolina at Chapel Hill (UNC). “The more we look, the more crazy things we see.”

Obelisks get their name from their distinctive shape and share similarities with viroids—small, infectious loops of RNA known to infect plants. Like viroids, obelisks lack the protein shells typical of viruses. Instead, they consist solely of circular RNA carrying genetic instructions. Unlike plant viroids, however, obelisks appear inside bacteria that live in the human body, particularly in the mouth and gut.

RNA itself plays many essential roles in biology. It helps translate DNA instructions into proteins, regulates gene activity, and can even catalyze chemical reactions. But obelisks represent something stranger: RNA entities that do not clearly fit into existing categories of life.

Thousands of distinct obelisk varieties have already been identified across genetic datasets from around the world. Their widespread presence suggests they are not rare anomalies. Genetic evidence hints that different types may prefer specific regions of the body, pointing to complex interactions with the human microbiome.

According to Matthew Sullivan, an integrative biologist at Ohio State University, the health implications remain unknown. Scientists do not yet understand how obelisks affect the bacteria they inhabit—or whether those effects could influence human health indirectly.

Their existence also raises deep evolutionary questions. Scientists have long debated whether viruses evolved from simpler RNA-based entities or became simpler over time. Obelisks may represent living clues from an ancient biological past, blurring the line between viruses, viroids, and entirely new forms of life.

“These entities don’t slide neatly into any existing box,” researchers note.

Their discovery suggests that entire classes of RNA-based life may have gone unnoticed simply because scientists lacked the tools to find them.

“This is one of the most exciting parts of being in this field right now,” said Simon Roux, a computational biologist at the DOE Joint Genome Institute at Lawrence Berkeley National Laboratory.

By Sabina Mammadli