Tell me a riddle in the form of a question.
What always runs but never walks, often murmurs but never talks, has a bed but never sleeps, has a mouth but never eats?
Complete the following task based on the instruction and optional input provided.### Instruction:
Tell me a riddle in the form of a question.

### Output:
What always runs but never walks, often murmurs but never talks, has a bed but never sleeps, has a mouth but never eats?