Answer:
What looks back but cannot see?
Hold the tail, while I fish for you.
A mighty weapon in the war against winged household pests.
Two in a whole and four in a pair. And six in a trio you see. And eight's a quartet but what you must get. Is the name that fits just one of me?
I work when I play and play when I work.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.