It was a tiny stoneware jug -- shaped like a face -- with broad lips, piercing eyes and leering teeth.
"It's been in my family since the '50s," said Hynes, who lives in Philadelphia, where her grandfather dug up the jug at a construction site in 1950.
"He was a plumber and they were building a school," she said. "He thought it might be some kind of Indian relic."
The jug moved from home to home, stored in attics and forgotten places. Hynes' grandfather died in 2002. He was 93.
Last fall, the jug re-emerged from a dusty china cabinet as Hynes helped her mother pack for another move.
"I knew it was something very special," she said. "So I started doing some research."
The jug turned out to be a piece of Edgefield pottery -- known for its distinct, greenish-brown alkaline glaze -- that was produced in the 1800s in South Carolina's Edgefield District a few miles northeast of Augusta.
In all, nearly two-dozen potteries thrived in the region, turning out storage jars and countless thousands of other vessels.
The face jugs -- of which only a few dozen are known -- are thought to have been made by slaves brought to the Georgia coast aboard the Wanderer, a schooner that landed near Jekyll Island in 1858, said Gary Dexter, an Aiken County potter and historian.
Of the 409 slaves who survived the voyage from their native Congo region of west Africa, 137 were transported up the Savannah River to a landing on the river's South Carolina side just opposite of Augusta.
Dexter said census records show some of them lived out their lives in the vicinity of the potteries, and likely worked there.
"The case for Wanderer slaves working in the area's potteries comes from the fact that the spooky-looking, crude face jugs showed up shortly after they arrived in 1858," he said.
The face jugs, he noted, are eerily similar to small statues made during the same time period by Congo natives and used to adorn bark baskets known as byeris.
The baskets had great significance and contained teeth or other sacred relics of their ancestors. The faces on those tiny statues were decorated with white kaolin clay -- the same material used to adorn the face jugs of Edgefield.
"Obviously, this was the single most important cultural item they had," Dexter said. "Just imagine them being chained and shipped across the ocean to here. They were probably trying to imitate this item in clay in the potteries where they may have worked. That is my theory."
Fragments of face jugs dating back as early as 1840 have been excavated in the area, but there is little doubt the arrival of young Africans aboard the Wanderer played a key role, said Steve Ferrell, who has studied the area's pottery for more than 40 years and operates the Old Edgefield Pottery studio and museum in Edgefield. "With their arrival, you have fresh blood, straight from Africa."
The Hynes jug found in Philadelphia, he added, could have been made by one of those slaves in the years after their emancipation.
"I would date the (Hynes) Philadelphia jug to the 1890s, due to the shape and form of the lip," he said.
Jill Koverman, curator of collections at the University of South Carolina's McKissick Museum in Columbia, said the complete mystery behind the face jugs of Edgefield might never be solved.
"What were they used for? That's still one of the big questions," she said.
The Wanderer connection is one of the best theories, although at least one white potter -- Thomas Chandler -- was known to make face jugs during the same period.
Oral histories, however, indicate one pottery in particular -- owned by Thomas Davie -- had 23 Wanderer slaves working there.
Today, many potters across the country make face jugs as contemporary art, she said, but authentic Edgefield face jugs from the late 1800s are quite rare.
"There are only a few dozen, maybe 50, and that's on the high side," Koverman said. "There has been a lot of research on them, but the puzzling part is that none of them are marked, with the exception of Chandler's piece."
Jugs similar to the one found by Hynes' grandfather are in collections at institutions including the McKissick, the Augusta Museum of History, the High Museum of Art in Atlanta, the Charleston Museum and the Philadelphia Museum of Art, which owns an Edgefield face jug donated in 1904.
There are also an unknown number in private collections.
Even if more were known about the origins of the Edgefield face jugs in general, there would still be a mystery behind the one now owned Hynes.
Somehow, it traveled from Edgefield to Philadelphia -- almost 700 miles.
Hynes isn't sure how it got there, or why it was buried, but she is working with producers of the PBS show History Detectives , which plans to air a segment on the jug later this year.
Afterward, Hynes plans to lend the jug to the Philadelphia Museum of Art, where it will be displayed for everyone to enjoy.