BERLIN (AP).- A 600-year-old skull believed to be that of a legendary German pirate has been stolen from a museum in Hamburg, the museum’s director said Wednesday. Klaus Stoertebeker was the most famous German pirate of the Middle Ages. He is believed to have been beheaded by authorities in 1400 in Hamburg, together with 30 of his followers. The heads were nailed on pillars at the entrance of the Hamburg harbor in an effort to deter would-be pirates. The skull was stolen from the Museum for Hamburg History on Jan. 9, but the museum didn’t immediately announce the theft so as not to hamper the investigation. It wasn’t clear how the exhibit was stolen, or why. “We are deeply shocked about the theft,” museum director Lisa Kosok said in a written statement. The museum said it was offering a reward of several thousand euros