Is Eywa a fungal organism?

[Human No More]

Originally Posted by Tiberius

No . Eywa does not work like the human brain, and there is nowhere in the film where anyone says this. Eywa displays abilities which appear supernatural, such as foreknowledge of the future (for example in the way she chose Jake). Although Eywa has a physical component, she also has a spiritual component. In an Interview James Cameron described Eywa as an "encompassing Spirit"

That's not knowledge of the future, or a group of angtsik would have killed Quaritch the moment he landed on Pandora.
It's intelligence, but not anything special.