Right under his nose

Here is a little story. I was looking at this short stretch of wall:

and an adjacent rock pile:

 (view back towards wall; according to my photos, there was another small pile at the lower end of the wall)

A small yellow lab ran up barking but wanting to be friends and I stopped to say hello to him and his owner. Since we had stopped right at this rock pile I thought I would poll the owner and asked politely: 

 - What do you think of that thing you are standing on?

- (him) What? I don't understand what you mean.

- I mean the thing you are standing on. 

- (him) Oh, this rock? 

He had a foot on one rock. I gestured at the whole pile and said something like (apologizing for intruding):

- No, I mean the whole thing

- (him) I guess it is a collection of rocks.

- Do you think it is man made? I ask

- (him) It's hard to say.

I pause and then say:

- It is not hard at all. 

Then we discussed the nearby wall, and agreed the wall was for some other purpose than the rock pile.