MARBLEHEAD – The razing of the former downtown YMCA building on Pleasant Street last week uncovered an unexpected historic dividend: a time capsule inserted in the “Y” cornerstone when the foundation was dedicated 100 years ago.The copper box was delivered to Abbott Hall and has remained in the Historical Commission office unopened.Historical Commission member Harry Christensen said local Inspector Chris Butler of the building commissioner’s office, son of town archivist Wayne Butler, went to the YMCA site and asked to have the building’s two cornerstones as historical relics.One of the stones was the cornerstone of the YMCA, built in 1910. The other was the cornerstone of a previous building.”The contractor cooperated and very carefully removed the two cornerstones,” Christensen said. “And lo and behold, one of them contained a copper box, soldered shut.”Although the “Y”‘s present owner is developer Heidi Wattendorf, the town is seeking a legal opinion as to the box’s actual owner – and Christensen believes it is the “Y.”He recalled a legal case in which a new buyer of the former home of Marblehead artist J.O.J. Frost found 30 Frost paintings under the attic floorboards, but the court awarded them to the previous owner, ruling that a house buyer purchases property, not what may be hidden there.That said, Christensen hopes the YMCA will agree to open the box at a televised selectmen’s meeting.Time capsules have been found in Marblehead before.This is the last surviving piece of the old YMCA, which moved to Leggs Hill Road two years ago and is now the Lynch-Van Otterloo YMCA.Historical Commission member William Conly said the box measures about 12 by 18 inches and 4 inches deep.He said Commission Chairman Paul “Chris” Johnson has contacted the YMCA and hasn’t had a reply yet.Despite repeated attempts, no one at the YMCA could be reached Monday.”My personal view is, this is not the property of the Town of Marblehead. It’s the property of the YMCA. It’s all up to them to open it and rightfully so,” Conly said.”It brings to light how many other time capsules there are in cornerstones throughout our town,” Conly added. “And people don’t know they’re there. They start to tear down a building and say, ‘Wow, look what we found.””If the contractor hadn’t seen it, it could have gone to the dump.”