They dug up the earth and found the skeleton of a newborn inside an iron box—what secret buried that child here?

“Stay,” said Monte Cristo, “here, in this very spot” (and he stamped upon the ground), “I had the earth dug up and fresh mould put in, to refresh these old trees; well, my man, digging, found a box, or rather, the iron-work of a box, in the midst of which was the skeleton of a newly born infant.”