Answer:
What is yellow, looks like the moon and has seeds?
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
Neither bought nor sold but more valuable than gold. It is built but not by hand. What is it?
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?