She said the small site was likely a stopover for traveling groups, a feature found throughout the state, and the soot is a good indication the ovens were used for cooking.
Environmentalists treasure Plum Island as a home to rare plants, a site where seals rest on rocks in large numbers, a stopover point for migratory birds and a habitat for endangered species like the roseate tern.
The airport offers free city tours to all travelers on a stopover of five hours or more and plays host to facilities such as an on-site swimming pool, butterfly garden, nature trail and cinemas.