Earlier I was on ARK Mobile. I have a massive wall around my base so my creatures can walk around in it. I went to my Doedicurus to put a saddle on it when I discovered it had almost 1300 stone in its inventory. Doedicurus when wandering autonomously destroy rocks to collect stones.
One cool think I found out is if you carry a tamed one with your Argy, hover over rocks and it will gather stone while being carried.. A damn hovering bulldozer💪.. (oh, same goes for Castroides and wood)