Hi Kudo....
If You move the rocks they are nothing worth... cause... some signs give a specifik direction... uo.. Down.. Right.. Left.. Booby Trap... Bomb... Granate...
yes. i agree. you are not digging for markers only. you have to get the gold or other treasure items. that rock depends on what meaning did the japanese put on that marker, if that is a marker at all. only the japanese know the meaning of the said markers.