A changeling’s fire developed as a defense mechanism to blind and escape predators and attackers, before they developed the capacity for natural shapeshifting, but after their hide became as chitinous and hard as it is.

A changeling’s sense of touch is somewhat diluted because of their hide, but not by much.  In their base form, a changeling’s chitin is hard and warm to the touch, both less yielding and less furry than a pony’s hide.