There was a legend.. the eyeless peoples.. most likely they had dark skin with blue mask, their eyes was missing so they just had a black eye socket with black liquid, they had it on their mask as well... Most likely they like organs to eat.. especially hearts..

One night everyone was sleeping but then woke up to bloody screamings they ran to the room seeing an eyeless and one of the solder laying on the floor blood covered he's chest and a hole in it.. the eyeless held he's heart..