Astrobiology, and Realistic Alien Design

Life on another planet may be very different from life familiar to us on Earth, but no matter where it lives, it must have the adaptations needed to survive in the environment it lives in. Consider the scientist in the picture here, looking into a hole in the ice at the arctic north. There is life underwater, in the cold and the dark, hanging upside down attached to frozen ice, which is quite alien and unfamiliar to most of us, and yet native to the Earth.

Sand in Black and White by John R. Canter

Xeric scratched his short beard. The young man thought for a long time on how to word his wish. You had to be careful with djinn, he thought, and efreet were even more dangerous than them. In the dark basement storeroom, a pair of fiery red eyes gazed impatiently through the smoke. What appeared to be a horned man had a grin on his face, trying to look trustworthy. It worked surprisingly well.