An international team of scientists has removed much of the mystery about Rocas Alijos, an isolated sea mountain in the eastern Pacific Ocean.

Scientists from the United States, including a fluid dynamics specialist from the University of Utah and others from Canada and Mexico, explored the extinct volcano for two weeks last fall, frequently battling the remnants of a hurricane.In some respects, Rocas Alijos is a modest version of the Galapagos Islands off South America, where many different species of life developed in isolation, says Patrick McMurtry, a U. assistant professor of mechanical engineering.

"When we first arrived at Rocas on Oct. 31, we could see, through very clear water, large tumbled boulders and hoards of colorful fish," says McMurtry. "The black rocks were surprisingly bare. On the underside, in protected niches, were many of the little creatures we expected to find - hydroids, an encrusting sponge, a small crab, many pencil urchins and a few fluffy algae." The species list is growing rapidly as experts from various institutions sort through the specimens.

Rocas Alijos consists of three basalt pinnacles that rise dramatically out of the ocean 200 miles off the coast of central Baja California. The rocks' importance in the study of the area's plant and animal life is increased by the fact that they lie at the boundary of two different biological zones: the temperate waters off California and the tropical waters off Mexico.

Although the rocks, remnants of ancient volcanoes, have been noted by sailors since at least the 18th century, no one is thought to have set foot on the craggy rocks before the international team.

Marine biographer Robert W. Schmieder, expedition leader, says scientists believe some of the marine life found attached to the rocks represents new species.

Rocas Alijos means "lightening rock," possibly indicating a place where ships might lighten their loads to stay float in rough weather. Alijos is also an archaic term for "smuggling," which could suggest a place where people stashed valuable goods for recovery later. But the recent Cordell expedition found no historic artifacts in two weeks of careful exploration.