I'll guess an old style of wall anchor (for concrete?) but since I can't find a picture of one online I'll concede that it's a weak guess. I do recognize that it's not a split anchor design like is used today, but I'm sticking with it.
At any rate, I believe its some type of hardware item, and that the X's along the base are intended to help hold it in place once it's put into use.
Does there happen to be threads on the inside (beyond the area where we can see that there isn't)?