In that case frankn it was really X marks the spot; I would never have suspected that. glad you found it. any other cache finders want to expand on the kind of markers used to mark a spot?
Overhead nail,spike, peg, on a beam or wall or even a lopped limb stub. Just add a string to mark spot below. Can a coat hanging nail in an outhouse mark a floor board?Or going up from it a spot above the top plate?
Pick a number regular. Count bricks or stones and add an off color if need be. Easy in and out even in the dark once eyes adjust.