Tombestone Tuesday--Flat Stones

A marble slab.  Surely that is the iconic image of a tombstone.  But there is nothing simple about those marble slabs.
This row of slabs are found in Everett-Big Prairie cemetery, also know as Community Cemetery.

 The four stones, all in a row are probably from the same era.  The left most above is a slightly different shape on top.  The next three all seem to be similar in shape and design.
The picture of this stone below was filed just before the above picture.  It looks like it could possibly be one of those three on the right.  The first of those has a streak across the bottom, like this stone.

The stone for Felix Matthews is is a simple slab, yet it has the image of the weeping willow with some additional carving in the top corners.  The inscription reads: Felix, son of Henry and Anna Matthews died May 17, 1860, aged 24 years.
The bottom of the stone has an additional verse but it is faint.  It looks to me that at one time, there must have been dirt or debris piled higher around the stone.  The dark streak across the bottom is a bit of a deposit on the stone.  And, since below that line, the stone is less decayed, I think something was protecting that area. Whether it was buried or not, it definitely was not exposed to the elements.
Either way, there is something special about the old marble slab.