I encountered these structures on a beach in Hong Kong (the Ham Tin Wan beach in Sai Kung country park). There were many of these structures and I have photographed two of them in detail and attached a larger image which shows the extent to which these were spread on the beach.
It seems these were made by an animal of some sort. All these sand deposits were organised around a single hole in the ground which presumably is the animal's home or hide out. And all such structures had a clear "walking" path which was almost a straight line. These paths had no sand deposits in them.
Am I right in assuming that these structures were made by an animal? If so, then which animal makes them? And what is the purpose of the round(ish) deposits of sand around the main hole? Are they an obstacle for predators?
Image 1: A structure in detail
Image 2: Another structure in detail
Image 3: Overview of structures