Made from humble material, Ossabaw Island's three tabby slave cabins now represent a historical and archaeological treasure of immeasurable value.

The 19th-century tabbies are "probably the most-intact examples of their type in North America," said Georgia state archaeologist David Crass. They represent "wonderful archeology that can give voices to those who were voiceless in our history books."

The cabins survived the Civil War, stood through hurricanes and dodged coastal development, a remarkable achievement, said Crass, because they "were never intended to be permanent buildings."

Built of a rugged mixture of oyster shells, lime, sand and water, the tabby structures represent a remarkable historic record by themselves. The artifacts they have harbored for decades add a second layer of significance.

Archaeologist Daniel Elliott, president of the nonprofit LAMAR Institute, led extensive excavations on the cabins in 2005 and 2006. Buttons, ceramics, bottle glass, tobacco pipes, nails, marbles, and bullets have been unearthed, along with a diversity of food bones.

One discovery was especially telling - a half-cent coin dated 1825.