Sand Bubbler Crab Burrows

At the Radhanagar beach on Havelock Island, Andaman islands, India, you can see these strange formations every day at low tide. If you watched for a bit, you could see tiny white crabs coming out of the hole, scooping up sand and rolling it into these tiny balls. Even cooler was that each crab seemed to have its own pattern, with some creating whorls, concentric circles, radiating rays, and many other patterns. I never got bored of looking at them while strolling along the beach. Some internet research suggests that this is their feeding method as they sort through the sand looking for small tidbits to eat.