Construction workers in the District unearthed an object weighing about 1,000 pounds that looked like a decades-old projectile for a big Navy gun, but it was unclear whether the apparent ordnance was explosive or inert.
     The discovery Wednesday prompted authorities to summon an Army explosive-ordnance disposal unit to the construction site at 4th and M streets SE.

Soldiers removed the object, which is shaped like the large shells fired by Navy warships. An Army spokesman was unable to provide more details.
  The site used to be part of the Washington Navy Yard and was once occupied by a Navy factory that manufactured large ordnance.

Work at the site was halted for about four hours while the object was removed.