If Bob Meistrell had found enough lobsters off the Los Angeles coast near fashionable Palos Verdes one winter day in 1975, then Christopher Columbus and Leif Erickson and those other European latecomers might not be facing another challenge for the title of America's discoverer.

But the scuba-diving Meistrell could find no lobsters in the murky waters, so he passed the time by digging for seashells 35 feet down. There he stumbled upon a relic of an ancient shipwreck that may force a rewrite of the textbooks.

It was a 280-pound stone with a hole in the middle, like a huge doughnut. The ensuing search for its origins was eventually joined by two marine archeologists in San Diego, several geology laboratories and scientists in Japan, Taiwan and China, a detective story spanning nearly seven years.

When the puzzle fell into place, there seemed but one conclusion: the Chinese discovered America.

Meistrell, his diving partner Wayne Baldwin, and marine archeologists Larry J. Pierson and Prof. James R. Moriarty III of the University of San Diego were not celebrities in their professions in 1980, when a Chinese historian who had been trying for years to dethrone Columbus published a brief, secondhand account of their work.

Now, in two long scientific papers, Pierson and Moriarty have published the full results of their research, describing how they unraveled the mystery and trying to anticipate questions from what they assume will be legions of skeptics.

"If we were in the Mediterranean, or the South China Sea, or the Indian Ocean," and found the same collection of relics in shallow water, "there would be no question of what it was, a shipwreck of great antiquity," Pierson said in an interview. "The controversy comes when you find that in the new world."

Defending their theory in the Anthropological Journal of Canada, Pierson and Moriarty acknowledged there was scant prior evidence of ancient Chinese voyages to America, but suggested that "early investigators were reluctant to report on intrusive evidence, fearing academic ridicule."

If Meistrell, co-owner with his twin brother Bill of the Dive N' Surf shop in Redondo Beach, had been less stubborn about recovering his odd find, the search might never have begun.

"Everybody complained . . . about it because it smelled, but it's my shop, so I left it there," he said.

Pierson had also made a living in the diving business, but in his 30s he decided to take a high school equivalency examination and go to college to study archeology. Moriarty, 55, a leading marine archeologist on this coast, now considers Pierson, 43, one of his top graduate students.

Pierson heard early about Meistrell and Baldwin's find and went down into the waters off Palos Verdes to see what else was there.

A year before, two U.S. Geological Survey scientists dredging 75 miles out in the Pacific pulled up a similar circular stone object 1,000 fathoms down, but what Pierson found off Palos Verdes was a quantum leap from that first small clue. The shallow bottom appeared to be covered wth stone relics, "and it was clear to me that this was pretty old, real old. The more I looked the more I was sure we had the remains of a shipwreck of ancient origin."

Since then, divers have brought up eight identifiable objects--five weight anchors, two more ballasts for compound anchors and one boom hoist counterweight. The turbulent waters had long since dissolved or carried away the remains of the wooden ship.

The stones were feldspathic sandstone. Analysts at the University of Minnesota, Los Angeles Valley State College and Taiwan National University concluded they could not have come from the Pacific Coast of North America, Pierson said.

Instead, the stones resembled samples from quarries on the southern Chinese coast. Their shape and size fit closely with anchors known to have been used by Chinese ships more than 2,000 years ago.

Pierson and Moriarty say there is no question the Chinese were able to navigate across the Pacific long before Columbus charted the Atlantic, particularly if they had a helpful push from the Japanese current.

"The Chinese had not only developed the balanced rudder--nearly 1,000 years before it appeared in Europe--but preceded in the use of watertight compartments and a form of the compass," they said.

The boat could have been a derelict, torn from an anchorage off Korea in a storm and carried across the Pacific without anyone aboard. But Pierson said one further discovery persuaded him that Chinese sailors were frantically trying to avoid the rocks at Palos Verdes.

Further offshore, 82 feet down but in a direct line from the site of the wreck, divers found two more stones of the same size and shape as the ballasts for the compound anchors. Pierson concluded these were the remains of two trailing anchors, flung overboard in desperation as seamen have done for centuries to avoid shoreline dangers.

In Pierson's view, the ship--a trader or even perhaps an exploratory vessel about 100 feet long--had lost its mast or rudder in a storm and had the misfortune of coming too close to one of the roughest parts of the southern California coast. Some of the crew may have survived, but, unlike Columbus, they had no way to get home and tell their story.

Yet Chinese historian Fang Zhongpu thinks he has proof that one Chinese explorer, a fifth-century A.D. Buddhist monk named Huishen, did return to tell the story of his 7,000-mile journey to a land called Fusang. Huishen's descriptions of the country's society and of something called a "Fusang tree" sound very much like ancient Mexico and the Mexican century plant, Fang and others contend.

Moriarty and Pierson are preparing rock samples to send to Fang in Peking so they can be matched by spectrographic analysis and atomic dating with stone from ancient Chinese quarries where Fang suspects the Palos Verdes anchors originated.

Meistrell says there are at least 30 more possible relics still underwater and he is keeping the exact location secret while trying to lease the site. Still, he takes a lighthearted view of his brush with history and tells friends he knew right away where the ancient anchor had come from: "Right on the side it said: 'Food to Go.' "