It's clear a 170-pound black boulder doesn't belong embedded half-a-foot into a sandy loam field north of Livingston.

The puzzle is whether it fell from the sky -- a meteorite on a collision course with Earth. Or if the giant rock was abandoned 10 feet off the road for some unknown reason, coincidentally about the same time residents saw a fireball burning in the Central Valley sky.

The missing piece of information should be known in a few weeks, if not sooner.

Jerry McAlwee, the self-described rock hound who found the boulder with a friend, hopes it's an extraterrestrial discovery. And even if it's not, the suspense is worth the time and effort.

"It's kind of a CSI-type thing," he said Tuesday. "If it's not a meteorite, I don't know how to explain some of the things (about the rock)."

For example, magnets stick to most of its surface. Part of its crust is melted and smooth. The grass is stained around it.

McAlwee, 40, lives in Sunnyvale but helps his girlfriend maintain five acres and a house about 100 yards from Highway 99. Along with a friend, Tim Mihalko, he was extending a fence on Sycamore Street.

Surrounded by grass, Mihalko thought he'd stumbled on a tree stump. As he made a closer pass with a ride-on mower, he realized it was a rock about the size of a microwave.

He called over McAlwee, who wasn't sure what to make of it. The last time he had mowed the field was early December. The object wasn't there. It would've mangled his mower blade.

After pondering a few theories, he wondered if it could be the remnants of the fireball seen in the night sky Dec. 27.

Several people in the state saw a tomato-green fireball flying northwest through the Central Valley. It sparked interest among meteorite hunters. A few are said to have spent some time scouring the area.

Meteorite researchers put the landing, if there was one, somewhere near the north Merced County line. No one has yet announced that they've discovered any pieces of it.

It remains to be seen whether this is from that event or some coincidence.

McAlwee sent a walnut-size sample to Eric Whichman, a San Diego resident who runs

Whichman said he will run preliminary tests to see if it contains nickel and iron, two minerals found in chondrites, the most-common kind of meteorite.

He'll also look for round mineral patches called chondrules. If both those pan out, he'll ship the sample to a lab for tests.

"We're taking a wait-and-see attitude," Whichman said.

Based on the photos alone, he's skeptical that it's a meteorite. If he was forced to make an immediate judgment, he'd say it's not a space rock.

If it turns out to be a meteorite, he said he'll visit Merced as soon as he can.

If it's not, he still wants to spend some time looking for any meteorite left by the fireball.

Regardless of how this mystery turns out, McAlwee looks at discovering the rock with a philosophical bent.

"Everyone lives between their alarm clock and their next meal," he said. "It broadens your idea of what might be the context of reality."

In other words, between a rock and a starred space.