"Like a native," the Doctor said with a grin. He plucked his glasses off his face a little awkwardly. He didn't have any reason to be awkward about his glasses around Jack, but still, there it was. His nose was large enough without his glasses making it more obvious.

He gestured for Jack to join him, and pointed out to the sea.

"It's moved," he said. "Do you see? With the light up, it's shifted its position, gone down. Possibly to pull sulfides out of the soil, maybe? Coming back up to respire at night?"