Keep in mind there won't be a perfectly clean boundary between the light and dark sides -- there will be a border area between the "night side" and "day side" t

Keep in mind there won't be a perfectly clean boundary between the light and dark sides -- there will be a border area between the "night side" and "day side" that is always in partial sun. Not that I think similar-to-Earth life is likely here (for other reasons), but theoretically you could find it on other planets with synchronous rotation, if you looked in that border area.