[Fauna]
Goobbues have an additional function to spread vegetation across the lands. On death, plants germinate from the corpse and spread in the nearby area. - (Can't remember quest) See corpse east of Drybone.
A species of grapes used to make prized wine was thought to be extinct after the catastrophy but was found on the back of a Goobbue in Raincatcher. (Quest from Wineport, can't remember name)
Unicorns are natives of Coerthas and are rarely seen. (Unicorn mount quest, WHM guild)
Horses exist but are not native to Eorzea. (Mentioned by one of the moderators)
[Flora]
If you look around the landscape, you'll notice that the flora scattered around are actually pretty detailed and unique, so much so it will be possible to document all of them.
Only catch is that most of the flora you see will be unnamed.
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From 1.0, if I remember correctly, Ascian natural form is that of a wispy Grim Reaper like creature. All beastmen fear them.