Part of the Mushroom Planet Series, which got me interested in Sci-fi at a young age. See my review of the first book, "Wonderful Flight to the Mushroom Planet". I found this book a bit weirder than the others. It made me less anxious to continue with the next book in the series, which I had a hard time finding a copy of anyway. So, I believe this was the last book in the series that I read.