Saw this occur for the first time a couple weeks back when one of my threesome couldn't find his ball marker. It was a small green marker, maybe the size of a dime, that kind of got lost for a while on the putting surface. I think the 3 of us spent about two minutes looking for it. To be fair there were a good amount of leaves on the green, but I would've bet that wouldn't have ever happened. My partner promptly threw out the green ball mark when we got back to the clubhouse though! I guess there's always something new to be seen on the course.