Originally posted by Draconifors:

I've also wondered about those particular structures.

I don't know why I've never dug around in the centre of it (I would guess if something is hidden there it would be in the middle) when I've been meaning to try for a long time now. :lunar2019smilingpig:

Be sure to take a wishbone (acquired from Bonemass) with you. It will tell you if any treasure is they right away with minimal digging.