"Brain in a Bag", catchy name. Seriously, who saves a brain in a bag and leaves it around a construction site? If I wanted a brain that bad (and yes, I could use a new one) I think I'd at least refrigerate it. And if it looked like a brain then it must have been fresh, otherwise it would have deteriorated to the point of mush. So thinking out loud here, supposing it is a human brain, to get to it they had to do some cutting, and would they only have cut open the skull and kept the brain or wouldn't they have dismembered the rest of the body too.