Today I found two natural bonsai of olive europaea. I think that it is the sylvestris variety based on the fact that the distance between the leaves is very small. Also, the way the leaves are arranged is more similar to the sylvestris variety than to the normal one that it's cultivated where I live.
Even if I'm not an expert in bonsai, I think that this is a real one and not a young tree because it's strongly branched, like an old tree. It seems just a smaller version of a bigger wild one. I found it on an old macera (a type of stone wall), so without much soil.
How could I know how old is it? If I put some photos here are you able to tell it (I didn't have a phone, so I didn't take any picture of it)?