The 500-pound bomb that Hurricane Sandy churned up at Guantánamo Bay, Cuba, turned out to be an unarmed replica of the real thing that American forces used years ago on training missions, the military said Wednesday.

It was an MK-15, also called a Mark-15 practice bomb, said Jose Ruiz at the Pentagon’s U.S. Southern Command in Miami, which has oversight on some operations at the remote base in southeast Cuba.

Navy divers were exploring the shoreline around a ferry landing for hurricane damage when they spotted the device Tuesday morning.

“It’s built to look like a bomb, to intentionally weigh the same as a bomb for loading purposes,” Ruiz said, adding it dated back to at least the Vietnam War era.

But it had no explosives.

The Navy shut down ferry service at Guantánamo while the base commander dispatched a plane to Mayport, Fla., to fetch a special bomb disposal crew to examine the item. The base reopened ferry service on Wednesday morning.

Ruiz said Navy divers were back in the waters of Guantánamo to see what else Sandy stirred up in the waters along the 45-square-mile base. The Mayport team advised them on potential “unexploded ordnance” they might encounter, he said.

“Obviously we’ve been operating at Guantánamo for many years,” said Ruiz. “Occasionally you’ll run into something like this.”

Base workers were still cleaning up the damage from last week’s Category 2 hurricane, notably debris and broken glass around the Pentagon’s crude Camp Justice compound that was built for the Sept. 11 and USS Cole death penalty trials.

The storm also tore up tents and tarps around the Expeditionary Legal Complex, where wind-driven rains seeped into buildings under the doors but caused no harm to the technology at the maximum-security war crimes court that beams proceedings to U.S. soil.

“There was no damage to the courtroom systems and electronics,” Navy Capt. Robert Durand said Wednesday. “Staff conducted an orderly takedown of the network in advance of the storm.”

Guantánamo’s recreational beaches were still closed Wednesday. Movies were once again being screened for troops, however, at the base’s open-air theater — Frankenweenie was Wednesday night’s Halloween feature.