@justus  
More like a T-rex.

Celestia is a cougar.

What an old horse.

Rood.

@Vinyl Fluff  
Yeah, they age but like really really really, slowly. (Journal of the two sisters). :)

@the metal bronyhead  

 
Official word is that neither of them share the immortal/long-lived attribute of Celestia/Luna.

know your mare

Doesn’t really matter does it? (hugs her)
 
BTW the “captain obvious” tag LOL!

Celestia is a horse

Celestia and Luna never age at all and now Cadence and Princess Twilight

Well she is an immortal Sun Goddess after all.

Celestia is a wise pony!

Rude.

Old but never ages she’s a god

That’s why she lets her younger sister do most of the things now. Celestia used to be quite active, like Luna is now. Now she loves to relax and get herself pampered: massages, spas, hugs, and so on.

She doesn’t look a day over 500.

I’m actually pretty young by alicorn standards.

Still best Princess!

@northern haste  
and water too

In other news we need air to live