They can clearly get "parts" like eyes, and limbs to match your imagination...but can they use the prehensile hair hex? :)
[Although all air elementals of a similar size have identical statistics, the exact appearance of an air elemental can vary wildly between individuals. One might be an animated vortex of wind and smoke, while another might be a smoky bird-like creature with glowing eyes and wind for wings.]
If they don't have hair, they can't make their hair prehensile. Even if they have an appearance that matches hair. The developers made it very easy to allow almost any creature to qualify, especially with the 'even eyebrows' reference. However, they are very clear that it has to be hair.
A gargoyle or stone golem carved to look like they had a pompadour, eyebrows, and a beard does not. A zombie (with hair remaining), a flesh golem (with hair remaining), or a carrion golem that somehow could use the hex would qualify. A hair or beard elemental probably could do it (if they existed), a stone giant (whose body is completely devoid of hair) cannot.
If you are a water elemental with a cascading waterfall of flowing locks (pun intended), that is not hair. Just like a disguise self to give yourself a beard wouldn't count as you having hair, you can't cast a spell that makes your claws do more damage if you don't have claws (I mean, obviously you can cast it, it just wouldn't do anything unless it specifically said it gave you claws too). Just like an ability the elongates your arms won't do anything if you don't have arms.
I gotta agree with Pizza Lord. The hex says it's gotta be "hair" (or eyebrows, moustache, beard etc). Just because an elemental looks like it has something comparable to hair... it's still only water or fire. Water and fire obviously aren't hair.
If the witch got hit with a "polymorph any object" and turned into the Mona Lisa, they couldn't use the hex even though the painting has hair... the "hair" is still just paint.
But! That did get me thinking!
What about fur? That's basically just hair, right?
Could a witch beast shape into a lion and use prehensile hair hex on the lion's mane? What about if they beast shape into a wolf? Could they use the wolf's fur?
Just a fun thought!
Cheers!
The witch can instantly cause her hair (or even her eyebrows) to grow up to 10 feet long or to shrink to its normal length, and can manipulate her hair as if it were a limb with a Strength score equal to her Intelligence score. Her hair has reach 10 feet, and she can use it as a secondary natural attack that deals 1d3 points of damage (1d2 for a Small witch). Her hair can manipulate objects (but not weapons) as dexterously as a human hand. The hair cannot be sundered or attacked as a separate creature. Pieces cut from the witch's elongated hair shrink away to nothing. Using her hair does not harm the witch's head or neck, even if she lifts something heavy with it. The witch can manipulate her hair a number of minutes each day equal to her level; these minutes do not need to be consecutive, but must be spent in 1-minute increments. A typical male witch with this hex can also manipulate his beard, moustache, or eyebrows.
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Construct type: no hair mentioned.
ELEMENTAL subtype:
Source Bestiary 6 pg. 303, Pathfinder RPG Bestiary pg. 311, Bestiary 2 pg. 307, Bestiary 3 pg. 305, Bestiary 4 pg. 305, Bestiary 5 pg. 305
An elemental is a being composed entirely from one or more of the four classical elements—air, earth, fire, or water—or the less common element called aether. An elemental has the following features.
• Immune to bleed, paralysis, poison, sleep, and stunning.
• Not subject to critical hits or flanking. Does not take precision damage, such as extra damage from sneak attack.
• Proficient with natural weapons only, unless it is generally humanoid in form, in which case it is proficient with all simple weapons and any weapons mentioned in its entry.
• Proficient with whatever type of armor (light, medium, or heavy) it is described as wearing, as well as all lighter types. Elementals not indicated as wearing armor are not proficient with armor.
• Elementals are proficient with shields if they are proficient with any form of armor.
• Elementals do not breathe, eat, or sleep.
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... While under the effects of a polymorph spell, you lose all extraordinary and supernatural abilities that depend on your original form (such as keen senses, scent, and darkvision), as well as any natural attacks and movement types possessed by your original form. You also lose any class features that depend upon form, but those that allow you to add features (such as sorcerers that can grow claws) still function. While most of these should be obvious, the GM is the final arbiter of what abilities depend on form and are lost when a new form is assumed. Your new form might restore a number of these abilities if they are possessed by the new form.
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now you could gain an elemental template BUT polymorphs don't change your type, just your form AND supernatural abilities based on form are addressed.
In a reach even the Paizo published artwork featuring elementals (that I recall) doesn't have hair. It's a good idea to find one that does as then at least some artist thought it would be cool.
I could say some bacteria have cilia and mammals have hair... but we need hair on the head or facial hair, not nose hair(thanks Stimpy-Rapunzel), or bodyhair, etc...
Commentary
Like with all things a bit odd, talk with your GM BEFORE you do it. Find a middle ground as to what will work in your Home Game. If it is harder than a DC 10 check, a good GM will have your character make a check and/or experiment in downtime to learn the outcome/boundaries.
For generic PF1 Game Balance it is a bit of a nitpick but you do lose abilities in a polymorph.
With prehensile tail you'd have a better shot.
