According to Ellen White, the serpent that Satan used as a medium was originally a beautiful, winged creature.
She describes its state before the fall in several places:
* "In order to accomplish his work unperceived, Satan chose to employ as his medium the serpent—a disguise well adapted for his purpose of deception. The serpent was then one of the wisest and most beautiful creatures on the earth. It had wings, and while flying through the air presented an appearance of dazzling brightness, having the color and brilliancy of burnished gold." (
PP 53.4)
* "The serpent was a beautiful creature, with wings; and while flying through the air, his appearance was bright, resembling burnished gold. He did not go upon the ground, but went from place to place through the air, and ate fruit like man. Satan entered into the serpent, and took his position in the tree of knowledge, and commenced leisurely eating of the fruit." (
1SP 35.1)