Forget drill contaminants, anti-freeze artifacts, and human skin cells, it’s finally time to bust out the most enduring quote of the nineties: Life will find a way. After much controversy and an array of scientific challenges, researchers are finally ready to confirm that life in Lake Vostok in Antarctica, which has been sealed up by four kilometers (2.5 miles) of ice for millions of years, doesn’t just exist — it thrives.

Skepticism was a natural reaction when reports first started coming in about the possibility of life in the subglacial Antarctic lake. Situated under four kilometers of ice, the lake is even more inhospitable than the surface directly above it; while drilling, researchers at Vostok Station measured the air at -89 degrees Celsius, the coldest temperature ever recorded on Earth. The ice above the lake puts the water under enormous physical pressure, comparable to that found under the surface of Jupiter’s moon Europa, but also cuts it off completely from the Sun. In such extreme conditions, and with essentially no outside energy input for millions of years, finding life in Lake Vostok seemed, let’s just say unlikely.

And yet, here we are. Having found living organisms in similarly isolated caves, in the burning mouths of volcanoes, and even floating in the Earth’s upper atmosphere, perhaps it shouldn’t have come as such a surprise to find life in these waters. In March, researchers confirmed the existence of a genuine Vostok-dwelling bacterium. It was a species never characterized before, which was exciting, but the assumption was that this was a plucky survivor hanging on by the skin of its teeth. Now, however, it seems the species revealed a few months ago is just one of a thriving community living in this most extreme of environments.

Over 3500 different species have been identified by a form of statistical analysis known as metagenomics. Basically, they sequenced all the genetic material in their samples at once, and used sophisticated analytical techniques to make sense of the resulting jumble of information. This technique has proven extremely useful in identifying species in an agricultural soil sample, for instance, but this is the first time its use has revealed a whole group of totally novel organisms.

In heading off criticisms, the team addresses the idea that much of this material might be contamination or ancient life lying dead but preserved since the ice was laid down. It’s impossible that the DNA could have persisted this long as a fossil, they say, but it’s even more impossible that the RNA could have; DNA’s older, more fragile sibling constitutes the best of their evidence in favor of living communities in Lake Vostok, as its half-life is far too small to be some molecular window into the past.

Most interesting is that the life they found is not entirely bacterial. Several hundred species of eukaryotic organisms also live in the water, including over 100 multicellular species. They even found species that are generally associated with mollusks and fish, leading one researcher to say that the lake “might have fish,” before quickly backpedaling.

The team does note that this wide swathe of deep-lake species includes members specializing in every stage of the nitrogen and carbon cycles, implying that the isolated ecosystem of Lake Vostok may have fixed, used, and recycled its own limited supply of carbon for several million years. If true, this means that evolution has invented the ultimate sustainable green-space.

As noted, the highly pressurized conditions in of the lake are similar to those found under the ice sheet of Europa. Many have speculated that this finding could imply the existence of life on that moon, but remember that life didn’t spontaneously form in Lake Vostok, but was laid there eons ago and simply managed to survive. If life exists in the underground waters of Europa, life still had to evolve on the moon at some point, in order to get down there.

This finding shows, though, how long life can survive on how little energy. Could life survive a trip through space on an asteroid? Lake Vostok shows us how few environments we really can discount in our search for life in the universe.

Now read: Researchers claim that life arrived on Earth via asteroids and comets, but not in the way you think

Research paper: doi:10.1371/journal.pone.0067221 – “Subglacial Lake Vostok (Antarctica) Accretion Ice Contains a Diverse Set of Sequences from Aquatic, Marine and Sediment-Inhabiting Bacteria and Eukarya”