Answer:
It's equally comfortable in an orchestra and a geometry textbook. What is it?
Whilst I was engaged in sitting. I spied the dead carrying the living
What is pronounced like one letter, written with three letters. And belongs to all animals?
Some live in me, some live on. And some shave me to stride upon. I rarely leave my native land. Until my death I always stand. High and low I may be found. Both above and below ground.
What can bring back the dead. Make us cry, make us laugh, make us young. Born in an instant yet lasts a life time?
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.