Just so you know, absolutely none of that is true.
https://en.wikipedia.org/wiki/Pyramidion_of_Amenemhat_III
I don’t know if the person who posted that is sincere or not, but plenty of people sincerely believe this sort of thing when it is posted on Facebook.
You say none of that is true, but it does, in fact, appear to be a black stone cut in pyramid shape with engravings.