Alright guys, so I have turned on my San Andreas and around the Tierra Robada entrance of Kincaid bridge, I stumbled upon a strange shadow underneath the ground. It is also casted on CJ. I have taken some photos of it. Here are the photos:
Random shaped (usually pentagons or circles) shadows exist all over this game, but most of them are in the countryside. Personally, I have no idea what they could represent. The location could mark out something and if we gathered all of these, perhaps it would create a pattern or lead to another mystery.