Potential signs of life discovered in volcanic glass that is 1.9 billion years old

Microscopic trails found in ancient volcanic glass have been identified by scientists as fossil traces left by bacteria that burrowed into rock around 1.9 billion years ago. This discovery reinterprets long-disputed markings as proof that life was actively searching for nutrients in one of the first seafloor habitats on Earth.

Where the hints were discovered

These paths are preserved in rocks modified by ancient hydrothermal activity by shattered volcanic glass between stacked lava flows in the Belcher Islands in Hudson Bay, Canada.

Dominic Papineau of the Institute of Deep-sea Science and Engineering (IDSSE) examined those formations and recorded the trails with minerals that demonstrate biological contact with the glass.

Each trail is made up of closely spaced, uniformly sized spheres connected by organic material; this pattern is more indicative of coordinated microbial activity than of haphazard mineral formation.

The setting itself limits how the features formed and suggests a biological origin that necessitates careful comparison with other rock structures because these traces are found among chemically altered vent deposits.

The significance of the paths

Because the rock preserves behaviour rather than actual bodies, researchers refer to the tracks as ichnofossils, or markings left by life rather than body remains.

Papineau discovered iron compounds and the phosphate-rich mineral apatite surrounding the spherical traces, which fit with the bacteria breaking down the glass.

Papineau said, "Trails of spheroidal ichnofossils composed of titanite and organic matter surround abundant nanoscopic-size apatite and lepidocrocite." Instead of passive mineral growth, that pattern suggests active nutrient searching.

Size begins to matter

The majority of the spherical traces were minuscule, with a diameter of only a few thousandths of an inch. While many nonliving material properties fluctuate significantly more, living cells frequently cluster around predictable sizes, therefore a tight spread is important.

Larger mineral bubbles in the same rock that were filled with calcite, a common rock mineral that is a kind of calcium carbonate, differ from strings of comparable spheres as well. That does not resolve the issue on its own, but it weakens the case for a random growth story.

An additional type of proof

Straight tubes ran side by side in other places among the same rocks, giving the evidence a second, unique form. The carbon-rich residue in those tubes was surrounded by titanite, a calcium titanium mineral, but the majority of them lacked the adjacent phosphate signal.

The forms appear less like scratches made by stray grains since no tube ended in a trapped crystal. The division between tubes and spheres indicates many biological processes, potentially multiple stages of preservation

Possibility of chemically active liquids

The rocks did not originate in a peaceful mud plain far from volcanic activity, but rather close to shallow seafloor vents. Hardened surface layers, rust-coloured mineral patches, and rocky spires all indicate the presence of hot, chemically active fluids flowing through the region.

Phosphorus and iron in new glass can be trapped in these areas, and as water seeps through the gaps, the minerals are continuously replaced. That environment makes it easier to understand how microorganisms could discover chemical energy and a rock that is malleable enough to change.

Living things' chemical signatures

The problem is further complicated by carbon and sulphur isotopes, which are heavier and lighter forms of the same elements. Significant levels of carbon were present in some of the material, and its chemical signature indicated that it most likely originated from living things.

According to Papineau, "stable isotopes provide complementary biosignatures for possible chemolithotrophy." These diminished values are consistent with chemolithotrophic life, in which microorganisms use dissolved chemicals and rock as a source of energy rather than sunlight.

Changes in chemistry following burial

Certain patterns in these rocks most likely developed after burial, when minerals and decomposing biomass interacted in the absence of living organisms. Instead of active tunnelling, Papineau attributes the rounded and layered formations to diagenesis, a chemical alteration that occurs after burial.

The Shunga-Francevillian Event, which signalled significant oxidation following Earth's early oxygen surge, is also echoed by similar carbon fluctuations. The paper avoids treating any odd texture as a fossil by separating these subsequent reactions from the trails.

Why the argument continued

Since later mineral changes might imitate ancient remains in volcanic glass, claims such as these have been met with scepticism for decades. This example has a live parallel because previous research on contemporary oceanic glass showed that bacteria may etch comparable textures.

Because the forms, surrounding minerals, and chemical signatures all align within the same vent-altered deposits, this rock formation—known as the Flaherty Formation—stands out. Although it raises the bar for any wholly nonliving explanation, this convergence does not eliminate ambiguity.

Wider ramifications of the study

This piece extends beyond a single set of Canadian rocks since volcanic glass is widespread on Earth and beyond. In the hunt for prehistoric life on Mars, impact glass has already been mentioned as a potential target.

Additionally, the paper recommends that future searches focus on clusters of clues rather than individual shapes. This warning is important since false positives can squander years in both Earth's earliest rocks and on other worlds.

The new image shows bacteria that altered volcanic glass, scavenged limited phosphorus, and left overlapping biosignatures throughout a battered vent system. The Flaherty rocks now appear much more alive than incidental, but contemporary seabed comparisons should test that theory further.