How to morph an object

Back in the day (like late elementary school/ early middle school) there was a book series "Animorphs".  The books were about a group of teenagers that got the ability to transform into animals (there were aliens involved as well but that's not relevant to this post)  I never really read the books, my older brother was more into them than I was. What I did think was really cool was the covers of the books.

Each book cover had one of the protagonists turning into a different animal and it was one of those hologram pictures, where from a particular angle you can see only certain of the images. I was pretty young at the time but I always enjoyed those covers. 

Later there was a television show on nickelodeon that only lasted a season or two. One of the effects on the show was the characters turning into an animal. Sometimes these were shown and sometimes they were implied by shadows and sounds. 

At the time I thought this was really impressive. Now, I know that they probably used after effects and that this doesn't even look that difficult (although I haven't tried it yet) 

I also found this tutorial on YouTube that shows how to morph objects. It is probably similar to what was used in the show. Enjoy