The story is that the Mercy Seat was found about twenty  years ago in a cave 20 feet below where the crucifixion of the LORD Jesus Christ took place at Golgotha. There was a crack in the rock above leading to the surface and the blood found on the ark was human. A book entitled: "Dead Men's Secrets" apparently contains details of this interesting claim. It remains to be seen whether this is a fact but it is an enthralling and tantalising possibility.
God bless you and God bless Israel ... KJS ... 06-Sep-2013