Scientists, who were earlier baffled by the finding of a jelly doughnut-shaped rock near Mars rover Opportunity, are now celebrating the discovery of life-friendly water traces on the Red Planet.

Reported in the journal Science, Jan. 24. the research article describes how the team of scientists found evidence of life-friendly water in Mars. "We've basically found strong evidence for clays on both sides of the planet," said co-author Steven W. Squyres, an astronomer at the Cornell University and principal investigator of the Mars Exploration Rover Mission.

In the report "Ancient Aqueous Environments at Endeavour Crater, Mars," the scientists said that the Opportunity, which has spent 10 years on the Red Planet, has discovered clay materials at the rim of Endeavour crater that require low-acidity, pH-neutral water to form, suggesting that there was once a neutral-water environment in the planet.

"Doesn't mean much to many people," said coauthor Raymond Arvidson of the Department of Earth and Planetary Sciences, Washington University in Saint Louis, Missouri said. "But to geologists, it's pretty exciting, because it's a clay mineral that forms in a particular aqueous environment."

The findings also give credence to Curiosity's last year discovery of clay fragments that are capable of hosting microorganism. Scientists, however said, that the new discovery does not prove that life existed on Mars. "These results demonstrate that early Mars was habitable, but this does not mean that Mars was inhabited," said report coauthor and lead scientist for the Curiosity mission, John Grotzinger. "Even for Earth, it was a formidable challenge to prove that microbial life existed billions of years ago."

The discovery of water comes close on the heels of scientists being left baffled by discovery of a pastry-shaped rock in a spot called Murray Ridge near Opportunity a few weeks ago. Dubbed as the "jelly doughnut rock", the mysterious object just appeared in the spot where there was nothing a few days earlier. "It's white around the outside, in the middle there's kind of a low spot that's dark red: It looks like a jelly doughnut," Squyres said.

The discovery had apparently excited scientists because it is something that the robotic rover has never seen before. "We're seeing stuff we don't normally get to see," Squyres said "This is an ongoing story of discovery. Mars keeps throwing new stuff at us."