Answer:
What goes in the water black and comes out red?
They can be harbored, but few hold water. You can nurse them, but only by holding them against someone else. You can carry them, but not with your arms. You can bury them, but not in the earth.
We are five little objects of an everyday sort, You will find us all in a tennis court.
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
Steals an event or even a mood. Reveals the truth or shatters it.
I am rarely touched but often held. If you are smart you'll use me well. What am I?