(Newser) - The latest thing out of industrial agriculture isn't too appetizing: Burbling up from the manure pits beneath factory hog farms is an oozing substance that's charmingly being dubbed "poop foam"—and it's un-charmingly explosive, reports Mother Jones. The ooze is wreaking havoc on large hog farms, trapping the toxic gases in manure and causing explosions in the upper Midwest—including one that killed 1,500 pigs. The worst part? Scientists are stumped to its cause. Perhaps more than 25% of operations in Minnesota, Illinois, and Iowa are now grappling with the issue, a University of Minnesota engineer says.