I too have thought it weird that there is a hole in the ground as a focal point. I have a theory that it may be connected too the rule of the hat. When Regina got the poisoned apple last season, not only was the ring with Daniel’s memory used as the last bit of magic, but it was also part of the trade to bring the apple in to our world. Knowing that. . . . what came in place of Emma and Mary Margeret into Storybrooke. Maybe it came out of the hole in the ground?