Please help me identify this

I understand this isn’t anything super crazy, and probably a reasonable explanation. My grandparents had this appear in the field next to their property in Michigan, and as the story goes, they were informed not to touch or take pictures. My grandpa being the guy he is, obviously doesn’t listen and actually removes a small piece, pictured. This has always been a “secret family story” because my grandparents thought it was a huge conspiracy back in the 70s, but I’m just looking for some clarif...

View original source