Informations about the new snapshot here: Wiki page about the snapshot 15w31a.

When a fold is pointed by a red arrow it means that that (I hate when I have to write "that that") fold is optional and you can remove it if you want.

I added the last image so that you can cover the inside of the Shulker in purple instead of having a white inside. Glue it to the back of the other part of the shell (the one in the first image with the folds) before folding the design.

This is not in the official Wiki buuut... IT WORKS AS A BLOCK!!! YOU CAN'T MOVE IT AND YOU CAN STAY ON TOP OF IT AS IF IT WAS A REAL BLOCK!!! IT EVEN WORKS WHEN IT OPENS ITS SHELL!!! And this is the first time that an entity can do that (excluding Tile Entities as chests), that's why it's cool! :D

Other search terms: End - Purple - Shell Lurker - Ender Golem - endergolem (actual texture file name)