遠目から見たときに、何か・・・鍵穴のような、何か？ とかって思ってしまいましたが、レンガの溝に沿って開いた出入り口でしたね。
When I saw it from far away, I thought that it would have been keyhole but it was the entrance of the ant nests that were along sides of the slots of bricks.
*not sure about my English...
