How long can you sit without moving? Ten minutes? How long can you sit in an empty room without getting bored? 30 minutes? How long can someone be trapped in a car trunk or a casket without losing their mind? A few hours? You know those Internet tests that ask what one song you’d pick to listen to for the rest of your life – what would you choose if the rest of your life was spent in a casket for 830 million years? If they could, a team of geologists might ask that of what appear to be microorganisms which have been trapped in 830-million-year-old rock salt crystal … and may still be alive! Somewhere in the fiction afterlife, Rip Van Winkle is thinking, “I’m not worthy!”
“Are microorganisms in Browne Formation halite alive?”
Even study co-authors and West Virginia University geologists Sara I. Schreder-Gomes, Kathleen C. Benison and Jeremiah A. Bernau wanted to know what was the biological state of the organic solids and liquids the found in halite from the 830-million-year-old Browne Formation of central Australia. In their study, published in the journal Geology, they remind us that halite is rock salt (sodium chloride) and not necessarily what one might find in a desert. However, the Browne Formation was once part of a saltwater sea dating back to the Neoproterozoic era and its abundance of halite indicates that the saltwater was a good medium for the growth of ancient marine microorganisms.
“As halite (NaCl) grows from saline surface waters, primary fluid inclusions entrap parent waters, becoming microenvironments within the host crystal. Microorganisms have been identified in modern and recent halite-precipitating waters.”
The team knew chances were good they would find some sort of microorganisms trapped in the halite in tiny saltwater bubbles, and those organisms would be the same age as the halite and the dirt from the Browne Formation surrounding it at a depth of between 1,480 to 1,520 meters (4,855 to 4,986 feet). The challenge is to examine the primary fluid inclusions without destroying the halite and whatever is inside them. For that in situ examination, they used transmitted light and ultraviolet–visible (UV-vis) petrography. That technique gave them what they sought.
“These objects are consistent in size, shape, and fluorescent response with cells of prokaryotes and eukaryotes and with organic compounds.”
Prokaryotes are single-cell organisms which include bacteria, and eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope. The petrography showed these organic solids looked like the microorganisms in a variety of states ranging from decayed to some that were unaltered and whose fluorescence matched that of a living organism. The researchers knew that another study found microorganisms living in 250-million-years-old halite formations that survived radiation exposure. Could theirs have survived more than three times as long?
“Therefore, it is plausible that microorganisms from the Neoproterozoic Browne Formation are extant.”
That’s science-speak for “Probably.” The microorganisms are not alive in the sense that they’ve been sitting in their locked room looking bored and listening to their favorite song until being discovered 830 million years later, but more like being in a state of dormancy or suspended animation which they can be revived from. Would that be a wise/safe/apocalyptic thing to do? The study doesn’t address that. Instead, it notes the potential of halite samples around the world to allow “exceptional preservation of organic matter over long periods of geological time.” Even more exciting, that same potential exists on Mars and some moons in our solar system. This transmitted light and ultraviolet–visible (UV-vis) petrography technique can be used to find life in non-terrestrial halite formations and study it in situ without destroying or freeing it.
is it time we honor rock salt for more than just melting our icy streets?