Answer:
What type of bar gets you wet walking in and out of it but keeps you dry inside?
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.
What can be heard and caught but never seen?
The more of it there is, the less you see.
Only two backbones and thousands of ribs.
It's what light turns into in the night