periostracum /per-i-osˈtrə-kəm/

The horny outer layer of a mollusc's shell

• hill and dale
• hillbillies
• hillbilly
• hill-digger
• hill-diggers
• hilled
• hillfolk
• hill-fort
• hill-forts
• hillier
• hilliest
• hilliness
• hillinesses
• hilling
• hillmen
• hillo
• hillock
• hillocks
• hillocky
• hill-pasture
• hill-pastures
• hills
• hillside
• hillsides
• hill station