@redweasel  
It’s generally implied with these types of images that there’s more going on than simple “encasement.” For example, in this very image, she’s breathing out a strange purple gas-like substance. Pretty sure a normal pone in latex wouldn’t be doing that.
 
Then there’s ones like this, were someone is turned and gains holes in their legs/arms as a changeling. Some amount of physical changes went on under there.  

 
 
And I personally like to think there’s some greater, deeper changes under that suit. In mind and body, Mercury has been changed.

@redweasel  
The material she was encased in is transforming her

does it really count as transformation, when it’s encasement?