Wasn't an attack event I was still in the same area only about 3 long boats distance away from the destroyed chests benches and pillars. It could have been some form of random monster spawn most everything destroyed was on the ground. but the strange thing about that is my castle is off the ground and I had a few stone floors destroyed inside the castle on raised ground right by my large fire pit. And the door was shut. My first thought was every time I placed a new stone structure things were destroying themselves. Then I wondered if I had forgot my password and a new player was running around using a hammer to pop random things but none of the items that were in the chests were missing. And if it was a player they could have griefed me worse by destroying my smelter or portals. They would have had to use and why not destroy things on their way? They would have to travel through 2 portals going through 2 other bases to get to the 1 they attacked.

It's just really random except for a few things in the same area all at ground level. But the few things inside the castle that were snapped to raised ground and were stone perplex me.