Perhaps because no one had anything that could add to your knowledge.
A little more elaboration, letting others in on what you ALREADY understand these to mean might go a long way to getting a response - such as why these would be used as a symbol.
Not everything inscribed on stone is a sign, not everything that resembles an animal or something else is man made.
Nature has had eons to shape stones, how do you know it isn't natural? Thanks.
Be well.