Quick quiz #239.

This document titled "Quick quiz #239" is from the journal New Scientist and contains a quiz with questions related to various topics. The first set of questions asks about the retention of juvenile features in adult animals, the alternative name for Enterochromaffin cells, the country where the oldest stone tools were found, the fluid in elbow and hip joints, and the association of Frank Wilczek and Steven Weinberg with a hypothetical elementary particle. The second set of questions presents a brain twister about finding the home prime of a number. The document also includes the answers to the quiz questions and a crossword puzzle. The solution to the brain twister is not provided and will be given in the next week's edition. [Extracted from the article]