Huorns

[Eyalan]

Huorns are mentioned in the book The Two Towers. (Flotsam and Jetsam) They were described like very powerfull and seem to be able to wrap themselves in shadow: It's difficult to see them moving, but they do.
Trees that had become queer and wild. Dangerous even, as Treebeard had discribed them. But still they followed the Ents into war.. strange?!
What are those creatures, and who made them? Does anyone have any ideas or lecture that goes deeper into the Huorns matter?

They are probably made by Yavanna as well, but would she make scary creatures like Huorns? Or could they have developed this way?

[Miluiel Greenleaf]

Perhaps with the lack of ent-supervision and guidance, they forgot the good ways and turned evil? Are not the huorns what attacked the Uruks in the movie TTT?