I have worked with those granite tables. They are made of solid rock 8 to 10 inch thick because they have to be heavy to avoid vibration.if you look at them you would never think some one could make a cavity in them place explosive in the cavity and then cover it so you do not even see the seams .....I know kitchen granite tops can be cut and then reconnected seamless.Iran makes large X-Ray devices for cars (detecting car bombs) and other items. So I don’t believe it. A simple x Ray machine would have shown the explosives.
So you would x-ray if you suspect something but in this case they just did not think how far these israeli bastereds go to damage the program.