Its an invisible thing but you can kill it with your attack even if you don't see it! Sometime you'll be able to see it hanging from the tree but they vanish,its a bit bugged!
Unlike the "Roaming Black Spirit" or "Aura of Failed Kzarka" you don't need to get the agro of this mobs.
See the screenshots in order to know where to hit (I was not able to trigger the "trap" so dont worry about that!).If you successfully hit it you will see a sort of black mist for a second, it mean you killed it. You can swap channel (My advice is to use guild channels) in order to hunt it for his knowledge. It does respawn at a normal rate tho.
In those screenshots you must find an "exploded cave" pretty easy to find, then from here just look arround for a specific tree that i highlited and hit a bush at the bottom of this tree.

https://imgur.com/a/vS6GoPT