Construction workers knocking out a wall in a building on Governor’s Island had a scare yesterday when they found what they believed to be a live, three-inch anti-aircraft round, police said.

Officers in the New York Police Department’s bomb squad responded and determined the round was inert and didn’t pose a threat. The 153-year-old building, no. 105, is in the island’s Arsenal District. The building is used for administrative offices.

Officials said they didn’t know whether the round would be deemed an archaeological find, but it isn’t the first time an excavation uncovered some interesting history on the island. Over the years, archaeologists have found Native-American burials, the remains of a 17th-century Dutch windmill, and what is thought to be one of the earliest European artifacts in New York, a trade bead, the co-author of “Unearthing Gotham: The Archaeology of New York City,” Anne-Marie Cantwell, said. “It’s a great historic resource for the world,” Ms. Cantwell, who is a professor of archaeology at Rutgers University, said. “The artillery shells could be something new.”

Seven graves from the early 18th or 19th centuries were also found in recent years near a parking lot. The remains are thought to be either those of British soldiers who defended the island or colonial American soldiers who were prisoners of war, Ms. Cantwell said. It isn’t clear how old the round discovered inside the wall is, but according to an official history, the island was home to Fort Jay during the early 19th century and operated as “an important supply base for Army ground and air forces during world wars I and II.”