As already known, Verdori is a steam dragon. He breathes the stuff, can shoot it, thrives in it. But during the winter, he doesn't have a way to keep his body temperature up enough to produce more when away from heat sources. So the spine was made to repair his damaged spine in an accident, regulate and keep heat in his system, and to expel excess steam.

The external shell acts as a chassis to boil water and send it throughout his body, as seen by the large green glowing tube. The big rivet like thing near his head acts as both a control panel and a flush system. Pushing down on it flushes all the steam built up in the dragon and release it through the pores out in the back. He can release steam out of the pores in the back willingly, but it won't completely empty his system. As one could imagine, use of the flush system will tucker him out quite a bit. The mechanical spine is also merged with his real spine and nervous system, it makes him stronger and a bit more resilient as a result.

Another few interesting things to know is that the spine glows a brighter green as his system is "fueled" or when the flush button is activated. When expelling steam through his breath or the flush function, his spine starts dimming noticeably until he needs to boil more over time or jumpstart himself by being near a heat source.
Done by  CROUTON