Answer:
What is it that given one, you'll have either two or none?
Take it and you will lose or gain more than all the others.
What is seen in the middle of march and april?
What has a head and a tail but no body?
What is something yet nothing, but if you fill it up it will disappear?
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.