Over more than half a century, the odd little stoneware jug inlaid with white porcelain eyes and fiercely bared teeth was stored in a china closet, then a shoe box, an attic, and a kitchen cupboard.

Ten inches tall and about 10 around, the vessel was a mystery to Robert Strang, a plumber who unearthed it in 1950 in the city's Mount Airy section. He was digging a sewer line in the 1100 block of Mount Pleasant Avenue, when a turn of his shovel exposed the pottery. With his boss' OK, he took it home, thinking it might be an Indian relic.

It wasn't.

The jug with a face is headed to the Philadelphia Museum of Art as a rare artifact crafted in South Carolina by some of the last enslaved Africans brought to America. Only about three dozen "face jugs," dating to the mid-19th century, are known to still exist. Experts put the value of Strang's find at $10,000 to $20,000.

The pot is so laden with arcana that PBS' History Detectives series plans to devote an episode to it this summer.

Robert Strang died in 2002 at 93, never knowing what he had found.

April Leopold Hynes recalls that her grandfather had intended to research the jug, dug up at the construction site of what is now Morris E. Leeds Middle School.

"It's a miracle that the shovel was gentle enough to keep it from breaking," said Hynes, a homemaker and part-time photographer from Washington Crossing.

Last October, while helping her mother and aunt move from their home in Ambler, Hynes asked them, "Where's that piece that Pop-Pop found?" They retrieved it from a kitchen cupboard.

Hynes wrapped the jug in a towel, took it home, and Googled Lenape Indian pottery. "I quickly realized it wasn't that," she said. "I looked at it again and said, 'This looks like it could be of African origin.' "

That track took her to the Smithsonian Institution's Web site, where she saw similar jugs with faces. From there, she connected with John Michael Vlach, a professor of American studies and anthropology at George Washington University. He knew exactly what she had.

"It wasn't made in Philadelphia," Vlach said. "This bad boy was made in South Carolina and somebody carried it up [North]."

Vlach, a specialist in African American and Caribbean decorative arts, said the jug was created shortly before 1860 in what was the Edgefield District, now part of Edgefield and Aiken Counties in South Carolina.

Face jugs have been made by potters throughout the United States. But ones like Hynes' - made with two types of clay, stoneware and porcelain - did not appear in this country until after 1858, when 170 enslaved Africans were smuggled into South Carolina on a ship named The Wanderer. (The international trade in African slaves had been abolished by the British in 1807.)

"The number of sites where African Americans were making pottery is really quite limited," Vlach said. "Edgefield sites are remarkable because the slave owners decided they could get their slaves to do something more complicated."

They chopped wood for fuel and mixed the clay, and through "watchful watching, they learned pottery," Vlach said. They "would make face jugs in their spare time or to break the monotony."

Gary Dexter, a South Caroline potter and historian, said it is not known how the face jugs were used, but that they were reminiscent of byeris, bark baskets from West Africa and the Congo that held teeth, skull and bone fragments of ancestors. Africans consulted the byeris before they planted, married or went to war.

They were decorated with crude wood faces "that looked almost identical to the Edgefield face jugs," Dexter said. "It is my opinion that they were probably trying to recreate one of the single most important things in their culture."

David Barquist, curator of American decorative arts at the Philadelphia Museum of Art, said Hynes' face jug would be on loan to the museum for display later this year.

The museum already has three Edgefield face jugs in its collection: two donated to the museum in 1904 and one in 1917.

Hynes' face jug is of particular interest, Barquist said, because it "has some kind of history locally, which is very exciting."

But that is one of the mysteries: How did it make its way from South Carolina to Mount Airy?

That could be hard to answer, said Sandra Chaff, archivist of the Germantown Historical Society. The land on which it was found, she said, was owned by the Samuel Unruh family from the early 1700s until its sale to Henry Lowber, a lawyer, in 1879.

Among the Lowber family were abolitionists, Chaff said. Although some might suggest that the face jug was brought along the Underground Railroad - the secret network that helped enslaved Africans find their way North to freedom - that could not be proven. "We can't even speculate on that," she said.

Historian Charles L. Blockson agreed, saying the Underground Railroad "was a clandestine operation" and that runaways carried very few possessions.

Blockson, however, provided the identity of The Wanderer's human cargo: Igbo people from West Africa.

One day, Hynes said, she hopes to know who created her face jug.

"I kind of feel it's my responsibility to find his name if I could," she said, "and find his story and tell it."

Contact staff writer Vernon Clark at 215-854-5717 or vclark@phillynews.com.