Washington ? The rocks scrutinized by the Mars rover Opportunity were born in a “salty sea,” scientists said Tuesday, further bolstering the theory that the planet was once wet enough to support life.

Building on findings first announced three weeks ago, the scientists said rock outcroppings in the crater where the rover spent almost two months display rippled markings that suggest water once moved across them. Their incredibly salty makeup also hints at a briny pool that, as it evaporated, left the rocks behind.

“This is a profound discovery. It has profound implications for astrobiology,” said Edward Weiler, NASA’s associate administrator for space science, at a press conference at NASA headquarters in Washington.

“If you have an interest in searching for fossils on Mars, this is the first place you want to go.”

Opportunity, one of an $800 million pair of rovers built by NASA, landed in a flat part of Mars called Meridiani Planum on Jan. 25. As it explored Eagle Crater, the small depression where it landed, scientists have become increasingly excited about what the rover’s trove of tools — including instruments that can grind at rock and analyze the minerals locked inside — was uncovering.

Steve Squyres, a Cornell University astronomy professor and the chief investigator for the rovers, said scientists didn’t know yet how long, or how long ago, the area was covered with liquid water. But the discovery does bolster the theory that Mars was, at one time, hospitable to some form of life.

“We don’t know that life was there, but we have an environment that was suitable for life,” Squyres said.

While the composition of the rocks would make them an excellent place for microbial fossils to be preserved, the rovers are not equipped to see something that small, Squyres said. But if they are there, future missions would be able to find them.

Three weeks ago, Squyres and others said they couldn’t tell whether the water that soaked the rocks was long-term or simply flooded them for a short time. But the patterns in the rocks, known as “crossbedding,” show the telltale signs that water at least 2 inches deep once rippled through the area.

“It’s a fundamental distinction — it’s like the difference between water you can draw from a well and water you can swim in,” Squyres said at a press conference.

What’s still unknown, he said, is what the discovery will ultimately tell scientists about the atmosphere and climate of Mars, past and present, and what caused its environment to evolve into the cold, dry place it is today.