It develops a weird translucent bubble where the sun hit:

I discovered this by accident, when I suddenly realized that the Adipose sitting on the windowsill was looking kinda funny.
Apparently the heat from the sun caused some sort of chemical reaction inside that started breaking down the gunk inside. Which we can now see through the translucent bubble:

Yuck.
(If you stumble across a cool Doctor Who thing, feel free to email me with a link.)


















