But, I have one last statement. To my knowledge, Natural abilities are dependent on your race. Isn't it Extraordinary if it is something you've learned?
Close. Na abilities are dependent on your physical form, but require no training at all. Note that lots of racial abilities are still Ex, even though they're "dependent on your race." For example, all bonus feats. Your ability to make claw attacks for no other reason than that you have claws is Na, but your Improved Grab ability (which is your actual skill with what you've got) is Ex... even if you got Improved Grab because of race. But your ending point... that everything that's learned is extraordinary (if it's not magical)... that's true.
All About Polymorph goes over this in pretty extreme detail, including going over the fact that Na abilities are gained even by Alter Self simply because being that shape gives you the ability, even if you'd never trained at being in that shape.
As to how we know "Spells" is an ability... well, first off it's listed under Special Attacks. Special Attacks are a subset of Special Abilities... that same Rules of the Game article (seriously, everyone should read it if they want to talk about this) even says
"Special Attack: A unique or unusual ability a creature can use to harm or hinder other creatures." Second, every single thing a character can do is an ability. Your flight speed? That's an ability (Na if you have wings, usually listed as Su otherwise). Your ability to breath air? Na ability. Your ability to get really angry? Ex ability if you're a Barbarian. All of these things are explicitly stated. If the ability is a really basic thing, it's Na. Otherwise, it's a special ability, in which case it's Ex, Sp, or Su.
I'm just going to post this and hope people read it, because it's important, all taken from that same Rules of the Game article which was on the very topic of "stuff you get with polymorph."
Special Attack: A unique or unusual ability a creature can use to harm or hinder other creatures.
Special Quality: A unique or unusual ability a creature has that is not offensive in nature.
Extraordinary Ability: Extraordinary abilities are nonmagical. They are, however, not something that just anyone can do or even learn to do without natural talent or extensive training. Effects or areas that negate or disrupt magic have no effect on extraordinary abilities.
Extraordinary abilities often depend on particular physical adaptations that a creature has. Changing form often strips the recipient of some extraordinary abilities, but grants some extraordinary abilities that the assumed form has. In general, when you assume a new form, you lose any extraordinary special attacks and special qualities you have unless you get them from a character class. You usually gain any extraordinary special attacks your assumed form has, but not the assumed form's extraordinary special qualities. That's because most extraordinary special attacks are based off gross physical features (such a big, nasty claws and teeth) while extraordinary special qualities tend to be subtler and largely derived from a creature's essential nature.
Spell-Like Ability: Spell-like abilities are magical. (They're also the subject of an earlier installment in this series.) A creature usually retains its spell-like abilities when it assumes another form because spell-like abilities are primarily mental in nature. You don't gain an assumed form's spell-like abilities when polymorphing or even when using the very powerful shape change spell.
Supernatural Ability: Supernatural abilities are magical but not spell-like. Some supernatural abilities depend on specific parts of the user's body, but most are derived from a creature's essential self. When polymorphing, you retain most of your own supernatural abilities, but you don't gain the assumed form's supernatural abilities unless you're using the shape change spell.
When a supernatural ability depends on part of your body that your assumed form does not have, such as a mouth for a breath weapon or eyes for a gaze attack, you lose that supernatural ability when in the assumed form.
Natural Ability: This term is a catch-all for just about anything a creature can do (or characteristic that it has) that is not extraordinary, spell-like, or supernatural. Natural abilities include most speed ratings (some very high speeds are not "natural," see the section on the alter self spell), mode of breathing (lungs, gills), natural armor and weaponry, general appearance, body type, and the presence or absence of the five basic senses (sight, hearing, touch, taste, pain). When polymorphing, you generally lose your own natural abilities and gain those of your assumed form.
So, what do we have here? First off, if it's a Special Attack, it's a special ability. It's right there in the definition of Special Attack (note: this is the only actual definition of Special Attack I've seen anywhere... usually the game just lists a bunch of them). Since Spells are always listed as a Special Attack, they're Special Abilities.
Okay, what's next? The SRD (this originally comes from the Monster Manual):
Special Abilities
A special ability is either extraordinary, spell-like, or supernatural in nature.
Note this is written directly after the bit on Natural Abilities in the SRD... seriously, do a search for "SRD Special Abilities" and have a look. It's very clear that Natural Abilities are separate from Special Abilities... they're the catch all for abilities that aren't special. So, we've established that spells are Ex, Sp, or Su. Now, there's a TON of different places that establish which one they are, but here's the simplest, from the Antimagic Field text (also available via the SRD):
The space within this barrier is impervious to most magical effects, including spells, spell-like abilities, and supernatural abilities.
So, spells can't be Sp or Su (they're separate) but they must be Ex, Sp, or Su. Well that was simple, wasn't it?
Now, there's other stuff. Occasionally the ability to cast spells has a listed type... it's Ex. Sp and Su abilities are defined by how they're not spells. Spellcasting is still explicitly allowed in an antimagic field (see the Rules of the Game on that topic) even though the spells themselves do nothing, which also indicates that the "Spells" ability isn't magic even if the spells themselves are. And so on. This comes up so often I usually forget which things I've said and which I haven't, but it's all there.
As to how we got on the topic... the original topic was "hey, you can remove spellcasting from a spellcaster if you can polymorph him into a specific shape!" But since that only works on willing (or unconscious) targets, it didn't matter, so that's kinda done with. But since the poster also claimed spells were Na abilities, I pointed out that they weren't. And this is more interesting anyway.
JaronK