I am just telling what's in the lore, and with the Navy saying these objects are trans-medium capable, and they enter the water, and we do not have the oceans mapped out, one can argue for underwater bases and we wouldn't have a clue. As for other evidence, per Carl Sagan, the Sumerian culture has sufficient oddities that it was likely the first contact civilization.

We can't duplicate the precisions of the pyramids today with our tech, so clearly there were advanced, ancient civilizations. Even science said, if humans disappeared today, there would be no ground evidence of human civilization after 100,000 years. You're not going to convince me of your position, especially when you're rolling your eyes, yelling argh, and using pejoratives. you wanted a conversation, i can list a thousand books of authored by well educated people, better than I, saying these things.