This book is fantastic and I'd definitely recommend it to adults. This was a series that came out in the 80s. The series included Asimov's Extraterrestrials, Monsters, Mutants and Ghosts. It was a FANTASTIC introduction to sci fi authors, because Asimov was the editor, and stories were chosen by Asimov, Martin Greenberg, Charles Waugh, and written by Piers Anthony, R.A. Lafferty, James E. Gunn and many others.
Each book is a selection of short stories about young ... whatevers, in this case, aliens. There's surprise endings galore, twists, thought provoking stories, some are short, some longer, all of them totally amazing. I read it when I was about 12 I think, and the back of the book recommends it for 8+ children.
I don't think they were written *for* children however. Some are absolutely heartbreaking.
These books are often available in second hand shops and if you see them- grab them!
I think I have Asimov's Monsters somewhere too.
Did anyone else read these books? :D