Sun baking

Since I first spotted it I notice that the tortoise is up sunning itself every morning on the corner of the platform around the duck house. When I first saw it a few days ago I thought it was fake, that, as a prank, a young adult had swum or waded out and put it there. I stared at it. It was so still it was easy to believe it was a toy but there was something about it, its real-ness that made me doubt. Then it moved its head a tiny amount.
It is always on the same corner. It has its back to the sun. The shell must work like a solar panel slowly warming its body throughout.