A bizarre little fungus, which scientists refer to simply as a ‘load of old rot,’ could change our understanding of the evolution of life on Earth as we know it. According to a report from the Washington Post, scientists from the University of Cambridge have made a discovery that fills in some of the biggest gaps in the history of life to date.

The first animals to wiggle their way onto land descended from ancient fish, some of the world’s first vertebrates. But before they could leave the primordial seas, the stage had to be set on land. Plants and other organisms colonized dry land long before animals, and researchers believe that this tiny fungus may have been on of the first terrestrial colonizers in the fossil record.

The fungus, known as Tortotubus, was described in the Botanical Journal of the Linnean Society. Scientists believe that some of the Tortotubus specimens unearthed could be more than 440 million years old.

According to Martin Smith, “There is a little bit of uncertainty with dating that particular specimen, so it’s possible the date will creep up a bit. It’s possible that more precise studies will revise the age, but I think it’s unlikely that this will make it younger than the second-oldest terrestrial fossil.” The Tortotubus fossil predates the next-oldest terrestrial fossil by 5 million years.

Despite the exciting discovery, scientists can’t be positive that Tortotubus was actually the first organism to leave the seas in favor of land. The fossil record has numerous empty spaces, and filling in one more spot is a far cry from definitively identifying the first living thing to live on land.

Despite the uncertainties, based on what scientists know already, Tortotubus was very likely to have been on the scene when terrestrial life first began. The fungus may have played a key role in precipitating the changes that paved the way for life on land, and is for now the oldest known terrestrial organism in the fossil record.

A press release from Cambridge describing the details of the study can be found here.