If you are unsure if a rock is a disguised golem or not, a spyglass shows their name and level even when disguised. Also, when disguised, the rocks often move slightly as you get close, re settling onto the terrain.
All rock elementals have the same rock skin when disguised. It is a bright yellow boulder and is very noticeable against dark mountains. Keep your distance, as they can aggro on to you when you get close.
If you're looking to slay one of these beasties, here's a clever way. You and a tribemate go out on an argentavis, one of you is driving, the other is attached to it via grappling hook with a rocket launcher and a good amount of rockets. Tried this with one of my tribemates and we had a blast.
If you notice a golem rock aboid if possible. If it's in the way of something important like a trail leading further up a mountain you can try kiting them out of the way. Use a fast and expendable mount like a raptor and aggro it by shooting arrows. Try moving unpredictably to avoid thrown rocks. They may lose interest midway, just shoot them and continue leading them out of the way. Once they get there keep your distance and they'll settle down in the new spot. Hope this helps.