Can anyone tell whether this is a drain cover or an electrical outlet cover? Former homeowners converted a garage to a family room ~20 years ago including extensive water drainage reorientation. The room appears to have been carpeted at one time. Photo shows a 5+11/16" circular brittle plastic cover with a 4" capsule-shaped recess holding two metal screws (rusted and stripped) on either side of a large 4-sided phillips-shaped indentation (shallow, stripped). Original color (grey? or white) obscured by cement treatment. It rises 3/8" above cement floor level. If it's an outlet, we want to use it; whereas, if it's a drain, we want to leave it alone.
My bet would be on it being a receptacle. Typically floor boxes like this are installed raised up a little, so as to accommodate carpet or other flooring.
I would also bet on it being a single outlet. Most likely the center cap is covering the outlet and the outer screws are there to hold everything on. Since we can see a shadow from the center box, I'd say pry it off of there as best you can.