"... for here dwelt the primeval spirit Moru [Ungoliant] whom even the Valar know not whence or when she came, and the folk of the Earth have given her many names.  Mayhap she was bred of mists and darkness on the confines of the Shadowy Seas, in that utter dark that came between the overthrow of the Lamps and the kindling of the Trees, but more like she has always been; ...."

The possibility that "she has always been" recalls Tom.  This differs from the origin other non-Maia nature spirits who existed at this time:

"These were fays (C); no one knows whence they came: they are not of the Valar nor of Melko, but it is thought that they came from the outer void and primeval dark when the world was first fashioned."

And the fact that even the Valar did not know her origin raises the likelihood that she was not of that order; but even this is uncertain, since in another of the Lost Tales, the Valar do not recognize the children of "Aluin, of Time, who is the oldest of the Ainur", and thus probably Ainur themselves, possibly born after the entry of the Valar into Ea.

The difference suggests that some other class of spirit existed (though still possibly "nature spirits" in a generic sense), not originating in the void and predating creation; if so, the phrase "she had always been" could be interpreted as her coming into being along with Ea.

Of course, I have no idea if this concept had enough breath to survive Tolkien's various baptismal dunkings, and if it was later transferred to Bombadil.