The Massachusetts State Police bomb squad exploded a pipe bomb Saturday on the Brant Rock Esplanade in Marshfield, State Fire Marshal Stephen Coan said. Someone reported a “suspicious object” in the 250 block of Ocean Streetshortly before 5 p.m., and Coan said the bomb squad identified the object as a pipe bomb. “It was so sensitive to shock that it went off and functioned as a pipe bomb is designed to, to set off and cause damage,” he said. There were no injuries or property damage, and an evacuation order had been lifted as of about 7:15 p.m. The incident is not believed to be related to the pipe bomb found in Worcester Friday, Coan said. The state fire marshal’s office and Marshfield Police were investigating.