When the Sea Withdraws, the Spawn of Cthulhu Find Shelter HereS

No, we haven't obtained early concept art from the sequel to Cloverfield. This structure is the home of an actually-existing seaside dweller on Earth. What kind of creature builds such a facehugger-esque structure?

Flickr macrophotographer P/\UL took this on a Texas beach, where tiny sand crabs tunneling under the sand kick up these dwellings as they disappear. Here is another shot he took, of the cracking surface of mud in Galveston.

When the Sea Withdraws, the Spawn of Cthulhu Find Shelter HereS

To me it looks like a wound in the hide of some impossibly huge sea monster from an alien world.

Images by P/\UL.