How do you imagine Sunnys shadows ?

Hey,

I started reading this novel and one thing bothers me ; I can't picture in my head Sunnys shadows. Does it stay on floors and walls like normal shadows ? But then when he tests his shadow in his room and the novel says "the shadow walks away ", does it mean that it's standing like a human ? Or when he tried to make it hit the towel in the bathroom ?

I'm curious about what you guys have in mind when reading the shadows moving related stuff