There is also one thing about Shapeshifters: They are endangered because back in the 1950s, people were sick of the Shapeshifters being a huge problem to the entire world, so they murdered every single Shapeshifter they can find. There are like 4 Shapeshifters left.
Here is a fun fact: Every single weapon (Except a Grenade Launcher) can't kill Shapeshifters.