Related Clues:

• Ming, the oldest animal ever discovered (400+ years), was one
• Don't talk, with, ''up''
• Bivalve shellfish
• The mute Marx Brother
• Marine mollusc
• Reticent shellfish?
• Burrowing marine mollusc
• Large shellfish with hinged shell
• Bivalve mollusc
• Mollusc with firmly-closed shell
• Edible mollusc
• Bi-valve with firmly-closed shell
• One is as uncommunicative as a mollusc
• It's one-fifty in the morning, so shut up!
• This ought to shut up our racket