Related Clues:

• Bit of dough
• Be silent, with "up"
• Smackeroo
• No blabbermouth
• Edible shellfish
• Dollar, casually
• Seafood in a shell
• Marine bivalve
• Uncommunicative sort
• Bivalve
• Ming, the oldest animal ever discovered (400+ years), was one
• Don't talk, with, ''up''
• Bivalve shellfish
• Marine mollusc
• Reticent shellfish?