Geologists in Australia have found evidence of mankind’s earliest ancestor – a 555 million-year-old worm-like creature smaller than a grain of rice.

Scientists on Monday said the prehistoric tiny worm, found in the Australian outback, represents one of the most significant primordial finds ever.

“It’s the oldest fossil we get with this type of complexity,” said Mary Droser, a professor at the University of California Riverside and among the scientists who made the discovery. “We knew that we also had lots of little things and thought these might have been the early bilaterians that we were looking for.”

Bilaterians are animals with bilateral symmetry, organisms that have symmetrical sides, a head, and openings on both ends connected by a gut.

Scientists have long agreed that bilaterians created fossilized burrows found in deposits in Nilpena, South Australia, but had been unable to prove it.

But new 3-dimensional laser scanning technology finally enabled researchers to identify the new creature, named Ikaria warjootia, as the culprit behind the burrows.

The organism is no bigger than seven millimeters long and less than two millimeters wide.

“We thought these animals should have existed during this interval, but always understood they would be difficult to recognize,” said Scott Evans, a doctoral graduate at the California university. “Once we had the 3-D scans, we knew that we had made an important discovery.”

The name of the creature was a nod to the original “custodians” of the land where it was found. It’s genus, Ikaria, means “meeting place” in Australian aboriginal language.

The name also comes from Warioota Creek in South Australia.

Despite a relatively simple shape, Ikaria was actually complex in comparison to other fossils from the Edicaran Period, which spanned 94 million years from the end of the Cryogenian Period 635 million years ago to the beginning of the Cambrian Period some 541 million years ago.

The creatures burrowed into oxygenated sand while hunting down organic matter and moved its tiny body by contracting muscles across its body like a worm, Droser said.

Evidence showing the creatures fed on organize matter revealed that Ikaria likely had a mouth, anus and gut, just like humans of today, Droser continued.

“This is what evolutionary biologists predicted,” she said. “It’s really exciting that what we have found lines up so neatly with their prediction.”

With Post wires