WASHINGTON (AP) — They came from Mars, not in peace, but in pieces. Scientists are confirming that 15 pounds of rock collected recently in Morocco fell to Earth from Mars during a meteorite shower last July.

This is only the fifth time in history scientists have chemically confirmed Martian meteorites that people witnessed falling. The fireball was spotted in the sky six months ago, but the rocks weren’t discovered on the ground in North Africa until the end of December.

This is an important and unique opportunity for scientists trying to learn about Mars’ potential for life. So far, no NASA or Russian spacecraft has returned bits of Mars, so the only samples scientists can examine are those that come here in a meteorite shower.

Scientists and collectors are ecstatic, and already the rocks are fetching big bucks because they are among the rarest things on Earth — rarer even than gold. The biggest rock weighs more than two pounds.

“It’s Christmas in January,” said former NASA sciences chief Alan Stern, director of the Florida Space Institute at the University of Central Florida. “It’s nice to have Mars sending samples to Earth, particularly when our pockets are too empty to go get them ourselves.”

A special committee Tuesday of meteorite experts, including some NASA scientists, confirmed test results that showed the rocks came from Mars, based on their age and chemical signature.