Answer:
A stellar five-Βlimbed sea creature.
Creeping on its belly, curled into a ring. Eyes forever open, beware its lethal sting
What is common to eat before it's born and after it's dead?
John Lennon sang about being this toothy creature.
What fish came first?
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.