u/Few_Enthusiasm8778

So this might have a very easy explanation but for me and my not so experienced friends this is a mystery - I am hosting this open pvp ARK server for me and my friends. Sever have been up for almost 2 months, we've never encountered anyone else but us on there. Then yesterday I randomly discovered a hidden base, we're talking a full metal base with 4 turrets stacked with ammo. So obviously this person have recourses and at least gotta have some levels. So naturally we had to blow it up and found a vault stacked with stuff, 100 C4, 100 missile and just random stuff normally found in higher lvl drops. Checked the logs since server start to see who this was, when they joined etc. Found like 10 people who joined for like 1-5 min tops and left. There is one guy who made it to like lvl 16, played for 15 min and then left. None of these players matched the name of who build the structures though? So my question is, how is it possible that someone built and gathered all this stuff and does not appear at all in the logs?