Is it possible to turn Rice Krispies back into rice?
Rice Krispies are made from a sweetened, malted and cooked and partially dried rice that is then "popped" similar to popcorn.

The manufacturer writes:


  Each piece is made from a single, toasted grain of rice (...)


The physical/chemical process is basically the same as for popcorn.
Unlike corn, rice grains contain very little water so the initial boiling step introduces enough humidity inside the kernel. The partial re-drying to harden the shell allows it to hold it inside while the water turns into steam and pressure builds. When the grain can't contain the steam any longer, it will expand and the gelatinized starch forms a sponge-like texture. Note that a careful balance of humidity and drying is required to get the best results.

As you are changing the structure of the starch, consider this a one-way process. Neither popcorn nor puffed rice can be transformed back to their original "kernel / grain state": 


  All the king's horses and all the king's men
  Couldn't put Humpty together again.




The "modern" puffed rice method using pressure / sudden release is attributed to Alexander P. Anderson, who stumbeled about it when testing the humidity of grains in the early 1900s. The process was taken over by Quaker Oats and used for other grains as well.