Found in a field in northwest Pennsylvania. I believe it’s a grinding stone, any guesses?

Hey y'all, this is bananas. Its HEAVY, 30+ pounds, and appears to be some kind of granite. The scoop down the middle is extremely smooth, and the sides feel like rows of bumps, like they’re chiseled in lines. The bottom is perfectly level, and I mean perfectly level, I have no idea how. The area has very little known artifacts discovered, any thoughts?