Aye, it’s likely sank into the ground under the weight of its own value. I had my stash at the top of a tower, after restart three heroic treasures missing. I removed the foundations that correlated to their placement and they were indeed on the ground.
Whether it’s worth the hassle of finding out is a different story, but I think those Derketo cat idols look neat and it’s a long boring walk off that ship.