Answer:
They are toothy nocturnal immortals.
What has a head, a tail, is brown, and has no legs?
In the middle of night, I surround the gong. In the middle of sight, I end the song
In the sun it likes to play; In the rain it goes away; Walk or run it always follows; In the mud it always wallows.
The lunch destination of choice for teenagers and hospital employees.
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?