What was Shelob, and more importantly, what was Ungoliant?

[obloquy]

Originally Posted by Gwathagor

I'm convinced by the suggestion that Ungoliant was a sort of anti-Bombadil incarnate-darkness evil-nature-spirit-in-spider-form. She's clearly not a Maia.

"Spirits" are termed ealar by Tolkien. There's no need for all the mumbo-jumbo, as 1) Bombadil has nothing to do with Ungoliante, 2) there's no reason to assume that Ungoliante was incarnate. You're right that she's "clearly not a Maia," but for the sole reason that she was not in the official service of any Vala; otherwise, her nature as a "spirit"--an eala--was identical to that of the Valar and Maiar.