I was looking through Summoner archetypes to decide what my end-goal for my next Pathfinder character would be build-wise, when i stumbled across the Spirit Summoner. I found the concept of my summoner having shaman abilities fascinating. However, there was one thing that was a bit unclear with how everything was worded under the Nature Spirit (which i have set my heart on considering the hexes). I noticed that under the True Ability that I would get if I made it to Lvl 17, my "Spirit Animal" takes the form of an Animal Companion, retaining its abilities and Int score and gaining the animal's abilities and other scores. However, nowhere in the archetype description does it say that Spirit Summoners get Spirit Animals.
So my question is when I get to Lvl 17, does my character gain an Animal Companion, have his Eidolon become an Animal Companion with its evolution pool, or ignore this ability?