[3.5] Incorporeal living creatures?

[CigarPete]

Are there any creatures that are able to become incorporeal or move themselves to the astral plane that would be accessible via Polymorph? Anything up to 15HD limit is available, though I would likely need to have seen/fought one to transform into it, per DM's current rulings, but most things are conceivable with a bit of research and I just got access to one of the largest libraries on the Prime.

I am aware of the Ghostform spell, but don't have it right now and getting new spells is problematic outside of spells available at level-up right now, and likely for the rest of the campaign. The library is not a spell library, but a historical one.

[Demonic_Spoon]

Unbodied (http://www.d20srd.org/srd/psionic/monsters/unbodied.htm) is the only thing that springs to mind.

[Biffoniacus_Furiou]

Anything with Psion Uncarnate (http://www.d20srd.org/srd/psionic/prestigeClasses/psionUncarnate.htm) 10.

[whibla]

Unbodied (http://www.d20srd.org/srd/psionic/monsters/unbodied.htm) is the only thing that springs to mind.

The problem is that unbodied are naturally incorporeal, and have no natural physical form. PSelf specifies that "you can't cause the subject to assume an incorporeal or gaseous form."

Other than the hit dice, the first thing that sprang to my mind was a Spirit of the Land, then I realised that wasn't really an option either, because of the whole incorporeality thing. They do, tbf, have the ability to take on an elemental manifestation, which is physical, but then their incorporeal subtype is listed as a special quality, which you do not get access to by PSelf.

Likewise, a phase spider's ethereal jaunt is listed as a special quality.

To rephrase, you're looking for a living creature that has a physical (non-incorporeal) form, is one of the types allowable by PSelf, and has an extraordinary special attack form or natural movement mode that allows itself to go incorporeal or plane shift to the astral plane?

I'm racking my brains, but coming up short...

[CigarPete]

no psionics for characters in this world, monsters only.

thought eater's ethereal jaunt, similar to the phase spider, is supernatural and therefore prohibited by polymorph.

Now, if only I could poly into a ghost...

[Urpriest]

Are you operating under the ruling that Polymorph grants spellcasting? If so, it's fairly trivial. If not, I doubt there's anything out there with Ex planar travel.

[Thump]

In savage species, I'm pretty sure there's a major ritual to get incorporeal, but it's expensive, and you still no longer have a STR score, but you get a deflection bonus = to your CHA mod, min +1. Also, do incorporeals have a CON score?

[Kelb_Panthera]

In savage species, I'm pretty sure there's a major ritual to get incorporeal, but it's expensive, and you still no longer have a STR score, but you get a deflection bonus = to your CHA mod, min +1. Also, do incorporeals have a CON score?

Savage Species also has the feat assume supernatural ability, though I don't remember if you can qualify for that via polymorph. As fo incorporeality's effect on abilities: the incorporeal subtype makes str a non-ability, but doesn't affect con. Since the majority of incorporeal creatures are undead, I can see why there might be some confusion.