Black Squirrels are kind of creepy, but it's fun to see them around campus. They may be good luck. They are very skittish, and this may be because they are mutants and the other squirrels try to kill them. This is just one theory, however.
Such squirrels are also common to specific trees and parkways on the 2200W block of Rice Ave in Chicago, as well as in Maddi Weiland's backyard in the Chicago suburbs. In the Knox area, they have reportedly been spotted near GDH, on the west side of SMC, and along Seminary Street. Maybe it was the same squirrel.