What is the signifcance of small stones placed on top of the ' Star of David ' at Jewish military war graves?

Question

What is the signifcance of small stones placed on top of the ' Star of David ' at Jewish military war graves?

Answer 1

It is a sign of respect and to 'show' the deseased that you were there. I'm sure there are a few other reasons too but that's what my father told me a long time ago and that's what I do when I visit my Jewish relatives grave sites.  

Answer 2

Each stone counts as a blessing.

Answer 3

do you want a funny answer or an uneducated one?

Answer 4

To keep zombie Jews from rising from the grave. They started this practice  when Jesus escaped from his resting place.

Seriously though, it is first off to mark a grave and show respect. It probably has roots to desert climate where sandstorms could otherwise devastate graves and dislocate markers if a heap of stones weren't piled on the grave.