Possible Clues:

• Milk-derived
• Acid type produced during exercise
• The acid found in milk
• What a broken clock may be without in the Milky Way
• If a clock were so milky it would be soundless, so it seems
• Sounds as if the clock won't go and do this in the Milky Way
• What a clock that's stopped will do, by the sound of it, in the Milky Way
• How a stopped clock might, by the sound of it, do this in the Milky Way
• Sounds like what a clock is missing when it makes no sound
• From milk