This Limited Edition item was available for 350 MC from May 6-28, 2010 and gave 1 xp when bought. The description reads "Contains 1 of 5 exclusive MC, animal themed surprises that can't be found anywhere else!". True to its description, all items inside the Animania Mystery Crate cannot be bought elsewhere. What you get from the Animania Mystery Crate is entirely random however, so there is no way to pick and choose, or to "increase" your chances. It is possible to receive the same item more than once if you purchase the crate more than once.
This crate is not the same object as the Mystery Crate or the Mystery Gift Box, nor will it give the same items as the other two. Everything found in the Animania Mystery Crate is a decoration (no pets or animals).