For 57 years, since its discovery by three rockhounds in the mountains of Eastern California, an oblong, 2- by 3-inch stonelike mass has been at the heart of speculation around the world.

Oh, how we want to believe that the truth is out there.

Was it a rock embedded 500,000 years ago with an electronic device left on earth by alien visitors? Or was it the remnant of a long-gone advanced civilization?

Beginning Saturday, you can see it for yourself at the Pacific Science Center.

Why all the speculation?

When the rocklike object was sliced in half shortly after its discovery, a perfectly circular, porcelain-like section was found inside it. In the center of that section was a tiny pin that responded to a magnet.

An X-ray clearly showed the metal pin, with a spring or helix at one end. The other half of the object showed metal covering the porcelain-like cylinder.