A city in Michigan has been hit by a downpour of black rain – after a tar-like substance covered cars, porches, and houses this week. The black substance began appearing in Harrison Township on Sunday, and residents and officials are baffled as to what the mysterious material is. Dailymail.co.uk reports: Michigan Department of Environmental Quality officials collected samples of the substance on Wednesday. The city’s fire chief sad that it is not bird droppings and is not flammable, according to WXYZ. Harrison Township resident Paul Schlutow, 73, said ‘everybody’s concerned’ about the substance and the major concern is that the substance could potentially be harmful. Residents originally believed that the substance could have come from the nearby Selfridge Air National Guard Base, but the base released a statement saying it was not coming from their location. ‘There is no indication that the substance in question came from a military aircraft of any type,’ the statement said. The statement said the airbase has ‘been in communication with the Michigan Dept. of Environmental Quality, which was sending a representative to the area in question to review the material’. ‘As Michigan’s Hometown Air Force, we take being a good neighbor very serious,’ Brig Gen [...]